The authors report the results of 58 children with ALL in 2CR after related (n = 31) or unrelated (n = 27) AHSCT. Characteristics at diagnosis and initial and after relapse antileukemic treatment were similar in the related donor (RD) and the unrelated donor (UD) groups. Conditioning consisted of TBI/CY +/- VP-16 for patients > or = 3 years old (n = 43) and Bu/CY for the rest. Median recipient age was 8 years (range 1-17) in the RD and 9 years (range 3-14) in the UD group. Median follow-up was 54 months (range 24-80) and 52 months (range 22-85) in the RD and the UD groups repectively. The 5-year EFS probability was 43 +/- 9% for the RD group and 36 +/- 9% in the UD group (p = .25). The transplant-related mortality was 16% in the RD and 37% in the UD group (p = .016). In the RD group 36.7% of patients relapsed versus 18.6% in the UD group (p = .05). GvHD associated with organ failure or infection caused most of the transplant-related deaths in both groups. Survivor quality of life for both groups was good (Lansky score < or = 90).