The ability of magnetic resonance imaging (MRI) to detect iron overload in children with end-stage renal disease (ESRD) was studied in 18 multiply transfused patients, aged 15.5 ± 4.8 years, and 5 nontransfused children without evidence of renal disease. In the transfused patients, the serum ferritin (SF) level was compared to (a) a subjective rating of signal intensity of MRI images (scale of 0–10), (b) mean Tl values of liver and spleen, and (c) computer-assisted measurements of spin echo intensity (SEI) of liver, spleen, muscle and fat tissue. On subjective evaluation, the mean signal intensity was significantly lower in transfused patients than in controls and a significant correlation with the SF levels was observed for ratings of both liver and spleen. Mean Tl values of liver and spleen did not correlate with the SF levels. On computer analysis, the ratios of SEI of fat/liver, fat/spleen, muscle/liver and muscle/spleen were significantly correlated with the SF levels as well as the subjective evaluation sorces. These data indicate that MRI is a suitable technique of documenting the presence and degree of iron overload in multiply transfused children with ESRD.