16 courses of an 8-drug regimen including daunomycin, vincristine, cytosinearabinoside, thioguanine, methotrexate, cyclophosphamide, prednisolone and hydroxyurea, and 12 courses of a 7-drug regimen including the same drugs minus hydroxyurea were administered in 16 otherwise therapy-resistant cases of acute myeloid leukaemia. In spite of a significant and rapid reduction of the leukaemic cell-mass in all the cases treated, only two brief minimal remissions were obtained. The main toxic effect was myelosuppression. However, the treatment was associated with a high frequency of mucosal ulcerations of the oesophagus and stomach, and it cannot be excluded that the latter complication may be drug-related.