Between 1985 and 1988, there were 3,393 children (Medicare insured) under age 20 who began treatment for chronic ESRD. Patterns of modality use, modality switch, mortality rates, and various aspects of transplantation were analyzed for different age and incident groups of this pediatric cohort. The pediatric cohort as a whole exhibited a distinct pattern of modality use when compared to adults in general, a point evidenced most clearly by their substantially higher rates of transplantation. Furthermore, notable differences were found within the pediatric cohort when the younger than 5, 5-9, 10-14, and 15- to 19-year-old age groups were analyzed separately. Younger pediatric patients, particularly those younger than 5 years, received peritoneal dialysis as initial ESRD therapy more frequently than their older pediatric counterparts. This result would be expected given vascular access problems often associated with very young patients. In addition, those patients younger than 5 years who began RRT with some form of hemodialysis had the highest likelihood of switching to CAPD/CCPD within the first year of therapy. Conversely, older pediatric patients were most likely to begin RRT therapy with some form of hemodialysis. By day 91, slightly over half of the 15- to 19-year-old age group was utilizing center hemodialysis; the CAPD/CCPD, other peritoneal, and functioning transplant modalities each contained about 10% of the patients with the remainder falling into the death and unknown dialysis categories. The overall pattern of switching to transplantation during the first year of RRT was similar for pediatric patients initiating RRT with center hemodialysis versus peritoneal dialysis (CAPD/CCPD), but differed by age group within each dialysis type. Pediatric patients on peritoneal dialysis were somewhat more likely to receive a transplant during the first year of ESRD compared to hemodialysis, although the difference was small. Mortality rates during the first year for patients who began treatment with center hemodialysis versus CAPD/CCPD were similar. The well-documented dominance of transplantation as a method of RRT for pediatric patients was further verified by this study. Results show that transplantation was implemented rapidly during the initial months of ESRD. Nearly 50% of surviving pediatric patients had a functioning transplant at 1 year following onset and 64% at 3 years. These percentages were exceeded for the 5- to 9-year-old age group, of which 74% had a functioning graft 3 years following onset.(ABSTRACT TRUNCATED AT 400 WORDS)