From Oct. '87 to Jan. '92, 69 pts were entered on this study, and 65 were eligible (2 lost from follow up and 2 wrong diagnosis): 38 (58%) boys and 27 (42%) girls, with a medium age of 4.75 years (range: 3 mos to 18 yrs). The diagnostic lesions were: bone 55 pts (85%), ear 22 (34%), skin 17 (26%), lungs 9 (14%), pituitary 8 (12%), liver 8 (12%), spleen 6 (9%), and lymph nodes 4 (6%). Thirteen pts (20%) showed organ dysfunction (O.D.): hematopoietic 10, pulmonary 8 and liver 5. We placed the pts on 3 groups: A) unifocal without O.D.; B) multifocal without O.D. and C) uni-or multifocal with O.D. The treatment for group A (25 pts) was surgery in 13, radiotherapy in 5, and no treatment in 7; for group B (27 pts) chemotherapy (Prednisone (PR) and Vinblastine (VBT) x 12 weeks) and for group C (13 pts) chemotherapy (VBT-Pr VP16-6 mercaptopurine and methotrexate x 52 weeks). The median follow up for all pts was 22 mos (range 1 to 52 mos). Group A had 22/25 pts (88%) without any evidence of disease; group B 9/27 (33%), and group C 1/13 (7%). Group A had a median event-free survival (MEFS) of 24 mos; in group B the MEFS was 4 mo (2 pts died in progressive disease) and for group C the MEFS was 1 mo (7 pts died in progressive disease). P between A and B is <0.001 and between B and C is <0.002. From 11 pts 5 1 year old (all of them with O.D.) 8 died in progressive disease, and only one is disease free. From 10 pts 2 1 to 5 2 years old (none of them with O.D.) all are alive and 5 are disease free. From 44 pts 2 2 years old (one of them with O.D.) 26 are disease free, and 2 died in progressive disease. The groups A and B had a very good survival; group B a chronic relapsing evolution and group C a gloomy prognosis. Pts 5 1 year old had a very had prognosis, hut in pts between one and two years of age the survival rate is as good as for pts 2 2 years old.