diff --git a/src/modules/product/controllers/product.controller.ts b/src/modules/product/controllers/product.controller.ts
index 09a2605..325c540 100644
--- a/src/modules/product/controllers/product.controller.ts
+++ b/src/modules/product/controllers/product.controller.ts
@@ -50,6 +50,7 @@ export class ProductController {
   @ApiQuery({ name: 'orderBy', required: false, type: String })
   @ApiQuery({ name: 'order', required: false, enum: ['asc', 'desc'] })
   @ApiQuery({ name: 'isActive', required: false, type: Boolean })
+  @ApiQuery({ name: 'parentId', required: false, type: String, description: 'Parent category id, or "null" for roots' })
   async findAllCategories(@Query() dto: FindCategoriesDto) {
     const result = await this.categoryService.findAll(dto);
     return result;
diff --git a/src/modules/product/dto/find-categories.dto.ts b/src/modules/product/dto/find-categories.dto.ts
index b6f37a1..3109844 100644
--- a/src/modules/product/dto/find-categories.dto.ts
+++ b/src/modules/product/dto/find-categories.dto.ts
@@ -36,4 +36,12 @@ export class FindCategoriesDto {
   @Type(() => Boolean)
   @ApiPropertyOptional({ example: true })
   isActive?: boolean;
+
+  @IsOptional()
+  @IsString()
+  @ApiPropertyOptional({
+    description: 'Filter by parent category id. Use "null" for root categories only.',
+    example: 'null',
+  })
+  parentId?: string;
 }
diff --git a/src/modules/product/repositories/category.repository.ts b/src/modules/product/repositories/category.repository.ts
index 31bc806..d95b7a5 100644
--- a/src/modules/product/repositories/category.repository.ts
+++ b/src/modules/product/repositories/category.repository.ts
@@ -11,6 +11,7 @@ type FindCategoriesOpts = {
   orderBy?: string;
   order?: 'asc' | 'desc';
   isActive?: boolean;
+  parentId?: string;
 };
 
 export type CategoryTreeNode = {
@@ -73,7 +74,7 @@ export class CategoryRepository extends EntityRepository<Category> {
   }
 
   async findAllPaginated(opts: FindCategoriesOpts = {}): Promise<PaginatedResult<Category>> {
-    const { page = 1, limit = 10, search, orderBy = 'createdAt', order = 'desc', isActive } = opts;
+    const { page = 1, limit = 10, search, orderBy = 'order', order = 'asc', isActive, parentId } = opts;
 
     const offset = (page - 1) * limit;
 
@@ -83,6 +84,12 @@ export class CategoryRepository extends EntityRepository<Category> {
       where.isActive = isActive;
     }
 
+    if (parentId === 'null') {
+      where.parent = null;
+    } else if (parentId) {
+      where.parent = parentId;
+    }
+
     if (search) {
       where.$or = [
         { title: { $ilike: `%${search}%` } },
@@ -91,7 +98,7 @@ export class CategoryRepository extends EntityRepository<Category> {
 
     const allCategories = await this.find(where, {
       orderBy: { [orderBy]: order.toLowerCase() as 'asc' | 'desc' },
-      populate: ['parent'],
+      populate: ['parent', 'children'],
     });
 
     const total = allCategories.length;