Abstract. BACKGROUND: Persistent urogenital sinus is one of the rare urogenital anomalies, which commonly presents as hydrometrocolpos. Fetal urinary ascites as a presentation of persistent urogenital sinus is extremely rare. CASE REPORT: We report on a preterm infant with antenatal diagnosis of hydrometrocolpos and massive urinary ascites secondary to urogenital sinus without any bladder or renal abnormalities. CONCLUSION: This case report emphasizes the importance of maintaining a high index of suspicion in the diagnosis of persistent urogenital sinus especially in infants presenting with urinary ascites along with hydrometrocolpos.