This study examined the consequences of nephrectomy in United States Army personnel who lost a kidney due to trauma during World War II (WWII). Records of 62 servicemen who underwent nephrectomy at an average age of 25 years were obtained. Mortality was compared with that of WWII servicemen of the same age. Medical records of 28 deceased subjects were reviewed for evidence of kidney disease. Medical histories were obtained and blood pressure and kidney function were assessed in 28 living subjects. Two subjects could not be located, and four subjects declined to participate. Mortality at 45 years was not increased in nephrectomized subjects. Kidney disease present in six of 28 deceased subjects was attributable to causes other than prior nephrectomy. Glomerular sclerosis was not increased in 10 subjects who had autopsy examinations. The prevalence of hypertension was not increased in living subjects. Five of 28 living subjects had abnormal renal function manifested by proteinuria greater than 250 mg/day in four cases (range: 377 to 535 mg/day) and serum creatinine levels greater than 1.5 mg/dl in three cases (range: 1.7 to 1.9 mg/dl). Conditions other than nephrectomy could have contributed to impairment of renal function in each of these subjects. These findings suggest that uninephrectomy in young adults has few major adverse consequences over 45 years.