OBJECTIVES: We evaluated functional outcome of kidneys with fetal urinoma associated to ureteropelvic junction obstruction. METHODS: We retrospectively reviewed 5 cases of antenatally diagnosed urinoma associated to hydronephrosis. Prenatal imaging work-up consisted of ultrasound (US) and magnetic resonance (MR) examination. Differential renal function was assessed postnatally with renal scintigraphy. RESULTS: Four male fetuses and 1 female fetuse presented with urinoma with hydronephrosis diagnosed by US at 24-25 weeks gestational age and confirmed by MRI examination at 28-29 weeks gestational age. On postnatal US, urinoma had disappeared in 4 cases. Parenchyma of the affected kidney was poorly differentiated in all cases. Ureteropelvic junction obstruction was confirmed in the 5 cases. Renal scintigraphy revealed poor functioning kidney (1%) in 2 cases, no function in 1 case, and impaired function in 2 cases (17%). CONCLUSIONS: Association of upper urinary tract dilatation caused by ureteropelvic junction obstruction and prenatally diagnosed urinoma may suggest a poor ipsilateral functioning kidney.