Urine ascites usually presents at birth or shortly thereafter and is associated with a high overall mortality rate. Posterior urethral valves are the most common obstructive lesions. Prompt recognition is vital if the survival rate is to be improved. Two unusual cases of urine ascites are presented. A stillborn premature infant with imperforate anus and massive ascites showed radiologic evidence of peritoneal calcification. A prepartum diagnosis could have been made from the radiographs of the maternal abdomen. The second case is unique in the presentation of urine ascites caused by a presacral neuroblastoma that produced bladder outlet obstruction and perforation.