The evidence in favor of transplanting single allografts from cadaveric pediatric donors into adult recipients is equivocal. This study was performed to assess the outcome of transplantation of single kidneys from pediatric donors weighing < 25 kg. Thirty-five adults transplanted by renal allografts from pediatric donors weighing < 25 kg were compared with 30 matched recipients of kidneys from adult donors. Donors in study group were aged 4.2 +/- 2.1 years weighing 16.0 +/- 5.3 kg. In the study group, surgical complications occurred in five of 35 patients, in the control group four of 30. Serum creatinine reached nadir in 47.5 days in study group versus 30 days in controls (P < 0.01). Serum creatinine at 1 and 3 years were comparable in both groups. A 38.9% had proteinuria at 1 year in the study group compared with 22.7% in controls (P = 0.36). One-year graft survival was 91.7% in the study group versus 92.8% for controls. The surgical complications and graft survival in the study group was comparable with that of controls. The incidence of proteinuria may be more frequent, but does not appear to impact graft function. The use of single, as compared with paired, pediatric donor kidneys would allow more patients to be transplanted with equivalent results.