Measurements were made of renal and glomerular hemodynamics and glomerular morphology in repetitively pregnant and age-matched virgin female Munich-Wistar rats. Repetitive pregnancies and lactation provide a stimulus to chronic increases in glomerular filtration rate (GFR) and these rats were studied, by micropuncture, approximately 4 to 6 weeks after the end of the fifth gestation/lactation cycle. No differences were seen in GFR or renal plasma flow (RPF) rate nor in any of the determinants of single nephron filtration rate (SNGFR) in repetitively pregnant compared to virgin rats, although SNGFR itself was slightly but significantly elevated in repetitively pregnant rats. There was no evidence of systemic hypertension, proteinuria, or abnormal glomerular morphology in either group despite their advanced age (approximately 42 to 46 weeks). Thus, the moderate chronic increase in GFR due to the stimulus of repetitive pregnancy and lactation does not lead to eventual deterioration in renal function or structural abnormalities.