Eighty 7-week-old female Charles-River rats were divided into the following groups: SV, sham nephrectomised and remained virgin; NV, underwent right nephrectomy and remained virgin; SP, sham nephrectomised and made pregnant a week later; and NP, underwent right nephrectomy and made pregnant. Each group was further subdivided into four equal groups given water, verapamil, captopril, and indomethacin respectively throughout the experimental period. Following delivery of the pregnancy groups all adult virgin animals and random groups of the offspring were sacrificed, and renal fractional fresh and dry weight as well as protein content were assessed. Results: fractional kidney weights and protein content (mg/kidney) were significantly increased in all nephrectomised adult virgin animals compared to sham-operated counterparts. Similarly, in the offspring of group NP the above parameters were significantly elevated compared to the offspring of SP. However, there was no statistically significant difference concerning these parameters between each of the subgroups within the same groups and its respective control given water. We conclude: (a) in rats, as in mice, post-nephrectomy elevated renotropin crosses the placenta and triggers extra growth of fetal kidneys, and (b) enhanced calcium influx via slow channels, angiotensin II, or increased intrarenal prostaglandin formation do not seem to play an important role in the exaggerated maternal or fetal kidney growth following maternal unilateral nephrectomy.