diff --git a/src/schemas/sro/relationship.schema.ts b/src/schemas/sro/relationship.schema.ts
index 5e0860a..0df7a32 100644
--- a/src/schemas/sro/relationship.schema.ts
+++ b/src/schemas/sro/relationship.schema.ts
@@ -8,6 +8,7 @@ import {
   type StixType,
   stixTypeSchema,
   xMitreAttackSpecVersionSchema,
+  xMitreDeprecatedSchema,
   xMitreDomainsSchema,
   xMitreModifiedByRefSchema,
   xMitreVersionSchema,
@@ -257,6 +258,8 @@ export const relationshipSchema = stixRelationshipObjectSchema
     x_mitre_domains: xMitreDomainsSchema,
 
     x_mitre_version: xMitreVersionSchema,
+
+    x_mitre_deprecated: xMitreDeprecatedSchema.optional(),
   })
   .required({
     created: true,