Out of 1603 patients registered in the German neuroblastoma trials, 29 patients (1.8 %) have preoperatively been treated according nephroblastoma protocols. Advanced stages (11 stage 3, 12 stage 4) were dominant. Diagnostic work up of those patients revealed elevation of catecholamine metabolites in only 39 % (compared to 80 % of the control patients) and mIBG uptake in only 71 % (compared to 89 % of the control patients). Elevation of NSE was observed in 92 % of patients (control group 72 %)