diff --git a/src/api/SIGCM2.Infrastructure/Persistence/ProductQueryRepository.cs b/src/api/SIGCM2.Infrastructure/Persistence/ProductQueryRepository.cs
index 4ee619b..0615f39 100644
--- a/src/api/SIGCM2.Infrastructure/Persistence/ProductQueryRepository.cs
+++ b/src/api/SIGCM2.Infrastructure/Persistence/ProductQueryRepository.cs
@@ -34,4 +34,16 @@ public sealed class ProductQueryRepository : IProductQueryRepository
         var result = await connection.ExecuteScalarAsync<int>(sql, new { ProductTypeId = productTypeId });
         return result == 1;
     }
+
+    public async Task<int> CountActiveByRubroAsync(int rubroId, CancellationToken ct = default)
+    {
+        const string sql = """
+            SELECT COUNT(1) FROM dbo.Product WHERE RubroId = @RubroId AND IsActive = 1
+            """;
+
+        await using var connection = _factory.CreateConnection();
+        await connection.OpenAsync(ct);
+
+        return await connection.ExecuteScalarAsync<int>(sql, new { RubroId = rubroId });
+    }
 }
diff --git a/tests/SIGCM2.Application.Tests/Products/Repository/ProductQueryRepositoryTests.cs b/tests/SIGCM2.Application.Tests/Products/Repository/ProductQueryRepositoryTests.cs
index 309e8e3..e557810 100644
--- a/tests/SIGCM2.Application.Tests/Products/Repository/ProductQueryRepositoryTests.cs
+++ b/tests/SIGCM2.Application.Tests/Products/Repository/ProductQueryRepositoryTests.cs
@@ -8,6 +8,7 @@ namespace SIGCM2.Application.Tests.Products.Repository;
 /// <summary>
 /// PRD-002 — Integration tests for ProductQueryRepository against SIGCM2_Test_App.
 /// These tests verify the real Dapper implementation replaces NullProductQueryRepository.
+/// Issue #41: CountActiveByRubroAsync tests added here (same class, same DB, same fixture).
 /// </summary>
 [Collection("Database")]
 public class ProductQueryRepositoryTests : IAsyncLifetime
@@ -44,7 +45,7 @@ public class ProductQueryRepositoryTests : IAsyncLifetime
     {
         // Arrange: insert a ProductType and an active Product referencing it
         var (medioId, productTypeId) = await InsertMedioAndProductTypeAsync();
-        await InsertActiveProductAsync(medioId, productTypeId);
+        await InsertActiveProductAsync(medioId, productTypeId, rubroId: null);
 
         var result = await _repository.ExistsActiveByProductTypeAsync(productTypeId);
 
@@ -56,7 +57,7 @@ public class ProductQueryRepositoryTests : IAsyncLifetime
     {
         // Arrange: insert an inactive product
         var (medioId, productTypeId) = await InsertMedioAndProductTypeAsync();
-        await InsertInactiveProductAsync(medioId, productTypeId);
+        await InsertInactiveProductAsync(medioId, productTypeId, rubroId: null);
 
         var result = await _repository.ExistsActiveByProductTypeAsync(productTypeId);
 
@@ -68,7 +69,7 @@ public class ProductQueryRepositoryTests : IAsyncLifetime
     {
         // Arrange: insert active product for productTypeId=A, query for productTypeId=B
         var (medioId, productTypeId) = await InsertMedioAndProductTypeAsync();
-        await InsertActiveProductAsync(medioId, productTypeId);
+        await InsertActiveProductAsync(medioId, productTypeId, rubroId: null);
         var otherProductTypeId = productTypeId + 100;
 
         var result = await _repository.ExistsActiveByProductTypeAsync(otherProductTypeId);
@@ -76,8 +77,65 @@ public class ProductQueryRepositoryTests : IAsyncLifetime
         result.Should().BeFalse();
     }
 
+    // ── CountActiveByRubroAsync (issue #41) ──────────────────────────────────
+
+    [Fact]
+    public async Task CountActiveByRubroAsync_NoProducts_ReturnsZero()
+    {
+        var result = await _repository.CountActiveByRubroAsync(rubroId: 99999);
+
+        result.Should().Be(0);
+    }
+
+    [Fact]
+    public async Task CountActiveByRubroAsync_Returns_CorrectCount()
+    {
+        // Arrange: insert a Rubro and products in various states
+        var rubroId = await InsertRubroAsync("Rubro Clasificados");
+        var (medioId, productTypeId) = await InsertMedioAndProductTypeAsync();
+
+        // 2 active products referencing the rubro
+        await InsertActiveProductAsync(medioId, productTypeId, rubroId: rubroId);
+        await InsertActiveProductAsync(medioId, productTypeId, rubroId: rubroId);
+
+        // 1 inactive product referencing the same rubro (should NOT count)
+        await InsertInactiveProductAsync(medioId, productTypeId, rubroId: rubroId);
+
+        // 1 active product with a DIFFERENT rubroId (should NOT count)
+        var otherRubroId = await InsertRubroAsync("Otro Rubro");
+        await InsertActiveProductAsync(medioId, productTypeId, rubroId: otherRubroId);
+
+        var result = await _repository.CountActiveByRubroAsync(rubroId);
+
+        result.Should().Be(2);
+    }
+
+    [Fact]
+    public async Task CountActiveByRubroAsync_WithOnlyInactiveProducts_ReturnsZero()
+    {
+        var rubroId = await InsertRubroAsync("Rubro Solo Inactivos");
+        var (medioId, productTypeId) = await InsertMedioAndProductTypeAsync();
+
+        await InsertInactiveProductAsync(medioId, productTypeId, rubroId: rubroId);
+
+        var result = await _repository.CountActiveByRubroAsync(rubroId);
+
+        result.Should().Be(0);
+    }
+
     // ── Helpers ───────────────────────────────────────────────────────────────
 
+    private async Task<int> InsertRubroAsync(string nombre)
+    {
+        await using var conn = new Microsoft.Data.SqlClient.SqlConnection(TestConnectionStrings.AppTestDb);
+        await conn.OpenAsync();
+        return await conn.ExecuteScalarAsync<int>("""
+            INSERT INTO dbo.Rubro (Nombre, ParentId, Orden, Activo, TarifarioBaseId, FechaCreacion)
+            OUTPUT INSERTED.Id
+            VALUES (@Nombre, NULL, 0, 1, NULL, SYSUTCDATETIME())
+            """, new { Nombre = nombre });
+    }
+
     private async Task<(int MedioId, int ProductTypeId)> InsertMedioAndProductTypeAsync()
     {
         await using var conn = new Microsoft.Data.SqlClient.SqlConnection(TestConnectionStrings.AppTestDb);
@@ -98,23 +156,25 @@ public class ProductQueryRepositoryTests : IAsyncLifetime
         return (medioId, productTypeId);
     }
 
-    private async Task InsertActiveProductAsync(int medioId, int productTypeId)
+    private async Task InsertActiveProductAsync(int medioId, int productTypeId, int? rubroId)
     {
+        var nombre = $"ProdActivo-{Guid.NewGuid():N}";
         await using var conn = new Microsoft.Data.SqlClient.SqlConnection(TestConnectionStrings.AppTestDb);
         await conn.OpenAsync();
         await conn.ExecuteAsync("""
-            INSERT INTO dbo.Product (Nombre, MedioId, ProductTypeId, BasePrice, IsActive, FechaCreacion)
-            VALUES ('Producto Activo', @MedioId, @ProductTypeId, 100, 1, SYSUTCDATETIME())
-            """, new { MedioId = medioId, ProductTypeId = productTypeId });
+            INSERT INTO dbo.Product (Nombre, MedioId, ProductTypeId, RubroId, BasePrice, IsActive, FechaCreacion)
+            VALUES (@Nombre, @MedioId, @ProductTypeId, @RubroId, 100, 1, SYSUTCDATETIME())
+            """, new { Nombre = nombre, MedioId = medioId, ProductTypeId = productTypeId, RubroId = rubroId });
     }
 
-    private async Task InsertInactiveProductAsync(int medioId, int productTypeId)
+    private async Task InsertInactiveProductAsync(int medioId, int productTypeId, int? rubroId)
     {
+        var nombre = $"ProdInactivo-{Guid.NewGuid():N}";
         await using var conn = new Microsoft.Data.SqlClient.SqlConnection(TestConnectionStrings.AppTestDb);
         await conn.OpenAsync();
         await conn.ExecuteAsync("""
-            INSERT INTO dbo.Product (Nombre, MedioId, ProductTypeId, BasePrice, IsActive, FechaCreacion)
-            VALUES ('Producto Inactivo', @MedioId, @ProductTypeId, 100, 0, SYSUTCDATETIME())
-            """, new { MedioId = medioId, ProductTypeId = productTypeId });
+            INSERT INTO dbo.Product (Nombre, MedioId, ProductTypeId, RubroId, BasePrice, IsActive, FechaCreacion)
+            VALUES (@Nombre, @MedioId, @ProductTypeId, @RubroId, 100, 0, SYSUTCDATETIME())
+            """, new { Nombre = nombre, MedioId = medioId, ProductTypeId = productTypeId, RubroId = rubroId });
     }
 }