Forty-five patients with acute myelogenous leukaemia (AML) received induction chemotherapy with either a conventional dose of cytarabine and daunorubicin (27 patients) or a low dose of cytarabine (18 patients). Maintenance chemotherapy was given to all responders. In 14 of 39 evaluable patients, infusion of fetal liver cells from 10-24 weeks old foetuses was given following induction as well as maintenance therapy. Six of 14 patients (43%) achieved a complete remission; 2 showed evidence of transient engraftment documented by analysis of sex chromosomes and RBC antigens (1 patient each). Fetal liver infusion within 6 days of completing induction chemotherapy appeared more effective than when given later. Five of 25 patients (20%) who did not receive fetal liver infusion achieved a complete remission. The present work suggests that fetal liver infusion given following induction chemotherapy may increase the remission rate in AML either by temporary engraftment or by accelerating the rate of haematological recovery.