The congenital anomaly of absence of the abdominal muscles is rarely seen and is constantly associated, when seen, with a variety of genitourinary anomalies, which always include hypertrophied bladder and usually include dilated and hypertrophied ureters, cystic degeneration of the renal tissues and cryptorchidism. These urinary anomalies are often associated with urethral obstruction of some type, and some authorities, notably Housden, have expressed the belief that urethral obstruction is present for at least an early part of fetal life in all cases of absence of abdominal muscles and causes secondarily dilatation of the bladder, pressure reabsorption of the anlage of the abdominal musculature, dilatation of the ureters, pressure dilatation of the renal tubules with cystic degeneration and nondescent of the testicles. However, there are few cases of absence of abdominal muscles reported in which an organic obstruction of the urethra was demonstrated—in fact, I believe only 2, 1 by Housden1