A 37-year-old woman presented with a painful mass lesion in her right inguinal region, 6 days after normal vaginal delivery. Computed tomography and magnetic resonance imaging showed a serpentine mass lesion containing blood elements along the inguinal course of the round ligament continuous to the labium majus. Although thrombosed varices of the round ligament is a rare condition, it should be distinguished from other inguinal masses to prevent unnecessary surgical treatments.