Eleven newborn children with clinical and anatomic characteristics of Prune-Belly syndrome were studied. This establish an approximate incidence of 1:28,000 newborns. All these children died in the first-days of life, nine of them as a result of pulmonary hypoplasia secondary olygohydiamnios. All of them except one had urinary tract dilatation and in four anatomic stenosis of urethra was found as the cause of obstruction. These findings support mechanical theory more than a primary mesodermic disorder as a pathogenic mechanism. All this, together with establishment of an early prenatal diagnosis, opens the possibility of an intrauterine treatment which could free the urinary tract and prevent oligohydramnios and its, sequelae.