Nineteen patients are reported who developed acute myeloblastic leukemia following treatment for a variety of solid tumors, including seminoma (four cases), melanoma (one case), and cancer of the ovary (six cases), colon or rectum (three cases), bladder (two cases), cervix, endometrium, and larynx (one case each). There were nine men and ten women, with a median age of 49.8 years (range 29 to 75). The mean interval between the diagnosis of solid tumors and acute leukemia is 5.8 years. In two patients the two diseases occurred simultaneously or within six months of each other. One patient was treated only surgically. Eight patients were treated with radiotherapy, five with chemotherapy, and five received both chemotherapy and radiotherapy. Pancytopenia was commonly noted prior to the onset of leukemia with chromosomal abnormalities observed in four cases in which a karyotype was performed. Three patients achieved complete hematological remission following antileukemic therapy. One hundred and six additional patients with non-hematopoietic neoplasms and acute leukemia are reviewed. Although acute leukemia may occur in a higher than expected frequency in patients with solid tumors because of a possible increased risk of a second neoplasm, it seems more likely that the acute leukemia is related to the radiotherapy and/or chemotherapy administered to treat the first neoplasm.