Rupture of the bladder in the neonatal period followed by urinary ascites is rare and usually the result of umbilical artery catheterization. Patients may present with abdominal distension, oliguria or anuria, and signs of renal insufficiency. We present a case of urinary ascites in a premature neonate due to a spontaneous rupture of the bladder, and we discuss the pathogenesis, diagnosis and management of this case.