Aim To standardize diagnosis and treatment of childhood Wilms tumor (WT) in Turkey. Methods & Patients Between 1998 and 2006, WT patients were registered from 19 centers. Patients <16 years with unilateral WT whose treatment started in first postoperative 3 weeks were included. Treatments were: stage I favorable (FH) and unfavorable histology (UH) patients, ‘VCR+Act-D’; stage IIA FH, ‘VCR+Act-D’; stage IIB FH, ‘VCR+Act-D’ +radiotherapy (RT); stage III-IV FH, ‘VCR+Act-D+adriamycin (ADR)’ +RT; stages II-III-IV UH tumors, ‘VCR+Act-D+ADR+etoposide’ +RT. Results 165/254 registered cases were eligible (bilateral, 5.9%) [median age 3.0 years; M/F:0.99; 50/165 cases £2 years]. 9.7% cases had UH tumors. Disease stages were: stage I 23.6%; IIA 36.4%; IIB 5.5%; III 22.4%; IV 12.1%. Cases >2 years had significantly more advanced disease. 1/11 cases with recurrent disease died; 2/165 had progressive disease, 2/165 had secondary cancers and all four died. In all cases four-year OS and EFS were 92.8% and 86.5%, respectively. Both OS and EFS were significantly worse in stage IV. Conclusions Despite problems in patient management and follow-up, treatment results were encouraging in this first national experience with a multicentric study in pediatric oncology. Revisions and modifications are planned to further improve results and minimize short and long term side effects.