Forty-seven patients with chromosome Philadelphia-positive (Ph1) chronic granulocytic leukaemia (CGL) in transformation underwent autologous transplantation of peripheral blood stem cells (ABSCT) collected at the original diagnosis before any treatment. They were treated with three consecutive strategies: single transplant (group I = 17 patients), double transplant (group II = 13 patients), double transplant followed by recombinant alpha interferon (group III = 17 patients). Forty-three patients were restored to a second chronic phase with a cytogenetic conversion (more than 10% Ph1-negative marrow metaphases) occurring in 14 of the 29 evaluable patients. Most patients had a recurrent transformation occurring 2-43 months after ABSCT and finally eight patients are still alive in second chronic phase 4-49 months after ABSCT (median = 24 months). The actuarial median duration of second chronic phase was 3 months, 10 months and 18 months for group I, group II and group III patients (P less than 0.0001). The encouraging results observed for group III patients prompt us to propose ABSCT for patients in chronic phase with initial prognostic factors, suggesting that recombinant alpha interferon will not be effective if administered as front-line therapy.