To assess the effects of changing therapy for treatment of chronic renal failure on cognitive function, 56 renal failure children were matched to healthy control subjects. Neuropsychological tests were administered every 6 months for up to four testing sessions. The renal subjects had reduced function on medical management, were being dialyzed or had transplants. Those renal patients who changed treatment groups over the course of the study were classified as good or bad change depending upon medical criteria. Those patients who remained in the same treatment group were classified as no change. Differences in performance between last and first sessions were analyzed for each pair. Renal subjects exhibited less improvement on memory function than controls but greater improvement on choice reaction time and vigilance. Renal subjects making a good change did not exhibit significantly greater improvement than other groups on neuropsychological tests.