diff --git a/internal/api/bom_handlers.go b/internal/api/bom_handlers.go
index e9d7315..119d6c3 100644
--- a/internal/api/bom_handlers.go
+++ b/internal/api/bom_handlers.go
@@ -19,6 +19,7 @@ import (
 // BOMEntryResponse represents a BOM entry in API responses.
 type BOMEntryResponse struct {
 	ID                   string         `json:"id"`
+	ParentPartNumber     string         `json:"parent_part_number"`
 	ChildPartNumber      string         `json:"child_part_number"`
 	ChildDescription     string         `json:"child_description"`
 	RelType              string         `json:"rel_type"`
@@ -424,6 +425,7 @@ func bomEntryToResponse(e *db.BOMEntry) BOMEntryResponse {
 	}
 	return BOMEntryResponse{
 		ID:                   e.RelationshipID,
+		ParentPartNumber:     e.ParentPartNumber,
 		ChildPartNumber:      e.ChildPartNumber,
 		ChildDescription:     e.ChildDescription,
 		RelType:              e.RelType,