Thirty unselected patients with chronic granulocytic leukaemia (CGL), age range 22-59 years, were treated with intensive chemotherapy and G-CSF to mobilize peripheral blood progenitor cells (PBPC). Chemotherapy was well tolerated and PBPC were collected by leukapheresis early during white cell recovery. PBPC collections considered adequate for engraftment were collected in 21 patients. Cytogenetic analysis of all collections in these patients showed >75% Ph negativity (range 79-100%) in 10. Successful collections, ie those >75% Ph negative and with total cell count of >1 x 10(6) CD34+ve cells/kg or >20 x 10(4) CFU-GM/kg were further analysed by Southern blot or RT-PCR. All samples were positive for the bcr/abl transcript. Patients with a low Sokal score (<0.8) were more likely to achieve a successful collection. In contrast, there was no association between transcript expression and likelihood of successful collection. We have confirmed that it is possible to mobilize and collect Ph-negative enriched PBPC in unselected patients with CGL. This procedure is more likely to be successful earlier rather than later in the course of the disease. Whether such collections will give an advantage over unmanipulated autologous bone marrow transplantation in CGL requires further study, but our experience suggests that suitable material for autologous rescue can be obtained from approximately one third of eligible, unselected young patients.