Background: An important loss of bone mineral density, associated to pain and fractures, has been reported in children with acute lymphoblastic leukemia (ALL). Aim: To measure bone mineral density among children with acute lympboblastic leykemia (ALL) that completed the remission induction phase with chemotherapy, that lasts 30 clays. Patients and methods: children with ALL, admitted to the oncology unit of a general hospital were considered eligible for the study. body composition and bone mineral density were measured by dual energy x ray absorptiometry (DEXA). each child with ALL was paired with a healthly control. Results: Fourteen children age 1 to 11 years, completed the study, Spine and femoral bone mineral density were significant lower than in their matched controls. No differences in total body bone mineral density or content were observed, Children with ALL bad a lower fat free mass and a higher fat mass than their matched controls. There was a significant correlation between fat free mass and bone mineral content. Conclusions: After one month of chemotherapy, children with ALL bad a lower bone mineral density in the spine and femur and a lower fat free mass.