One hundred and seven untreated patients with acute myelogenous leukemia (AML) were admitted to St. Bartholomew's Hospital between the 10th October 1970 and the 31st January 1973. Before receiving drugs to induce remission they were allocated alternatively into 2 groups to decide their remission treatment, a group to receive chemotherapy alone and a group to receive the same chemotherapy with immunotherapy. The patients were then given induction chemotherapy and 45 of them attained complete remission. All patients in remission then received chemotherapy consisting of 5 days treatment every 28 days. Patients receiving immunotherapy were also given multiple weekly intradermal injections of irradiated stored AML cells and Glaxo BCG using a Heaf gun. There were 19 patients in the group which received only chemotherapy during remission; 7 of these patients remain alive (median survival after attaining remission--303 days) and only 5 are still in their first remission (median remission length 188 days). Twenty three patients were allocated to receive immunotherapy during remission in addition to chemotherapy and 16 remain alive (median 545 days) and 8 are in their first remission (median 312 days). The difference in survival of the 2 groups is significant with a sigma value of 0.003.