Renal function and blood pressure were assessed in 52 renal allograft donors 10 years or more following uninephrectomy, and their current function compared to their pre-uninephrectomy function as well as to age- and sex-matched control subjects consisting of inpatient potential renal donors and a normal "outpatient" population. The results show no significant deterioration in renal function as determined by serum creatinine or creatinine clearance, as a function of years post-uninephrectomy or age at the time of donation. A higher incidence of proteinuria and hypertension was found in male donors as compared to their pre-uninephrectomy values and to age- and sex-matched, inpatient and outpatient control subjects. Female donors had increased proteinuria when compared to pre-uninephrectomy and to age-matched, inpatient potential donors. However, the extent of proteinuria and hypertension was not significantly different from outpatient age-matched females with two kidneys. In our population, uninephrectomy is associated with mild proteinuria and hypertension.