Postoperative renal impairment has been reported after kidney-preserving resection of retroperitoneal neuroblastomas (NB). To avoid renal damage, intraoperative procedures include monitoring of central venous pressure (CVP) and diuresis, i.v. administration of electrolyte solutions, mannitol, and furosemide, and local application of lidocaine to the renal vessels. During the first 5 postoperative (p.o.) days, CVP, diuresis, body temperature (T), and lactate dehydrogenase (LDH) levels were monitored; color Doppler ultrasound (CDUS) was also performed on the 7th p.o. day. Simultaneous increases of T (>38.5 degrees ) and LDH (>1,500 IU/l) and/or reduction of urinary flow (< 1.5 ml/kg.h) were indicative of renal damage: in these cases dopamine was administered and CDUS performed. If renal blood flow was normal on CDUS, dopamine was administered for another 2 days; if a vascular thrombosis was detected, fibrinolytic agents (urokinase 4,000 IU/kg bolus and then 4,000 IU/kg.h for 24 h) were utilized. Between May 1997 and June 2000, 29 children (9 F, 20 M, aged) 6-72 months (median 39) affected by grade II inoperable, grade III, and grade IV NB underwent these preventive procedures at the time of surgical excision of the mass after chemotherapy 23 had an uneventful p.o. course. CDUS at 7 days was normal in 22; in 1 (polar resection at operation) it demonstrated a slight reduction of blood flow in the renal cortex. For all 23 patients, the CDUS at 3, 6, and 12 months was negative. Three patients showed a single altered parameter; the CDUS p.o. and during follow-up did not show any alteration. The other 3 patients had two or more altered parameters and were treated with dopamine: in 1 the initial CDUS was normal, but it later showed moderate hypotrophy; in 2 patients a vascular thrombosis was documented. Treatment with urokinase was successful in only 1 patient who had a normalized CDUS after 3 months. The 2nd child developed renal failure and needed hemodyalisis. In our experience, elevation of serum LDH and T and/or oliguria were good indicators of renal impairment. CDUS was also useful in detecting renal blood flow reduction and artery occlusion. These preliminary results show these intra- and postoperative measures to reliably avoid renal impairment in these children. Long-term follow-up could confirm the efficacy of these methods.