PURPOSE: To analyze the type of prior tumor and treatment in therapy-related acute promyelocytic leukemia (tAPL) that occurs after chemotherapy and/or radiotherapy (RT), and the hematologic characteristics and outcome of tAPL. PATIENTS AND METHODS: Sixteen patients with tAPL who were gathered during a 10-year period (1982 to 1991) in seven hematologic centers were analyzed retrospectively. RESULTS: There were 13 women and three men. The median age was 46 years (range, 12 to 82). Prior tumor was breast carcinoma in 10 cases, another solid tumor in three cases, and lymphoma in three cases. Two patients had received RT alone, and 14 had received chemotherapy (with RT in 11 cases). Prior chemotherapeutic agents generally included a combination of cyclophosphamide (used for limited periods), fluorouracil (5-FU), vinca alkaloids, and doxorubicin, mitoxantrone, or etoposide (VP16). By contrast, alkylating agents other than cyclophosphamide had been used in only two patients. Median interval between onset of treatment for the prior tumor and diagnosis of APL was 25 months. No patient had a known preleukemic phase. Hematologic and cytogenetic characteristics of the cases of tAPL were identical to those of the usual de novo APL, which included the presence of t(15; 17) in nine of the 10 patients tested. Two patients had early death. Seven patients were treated with intensive chemotherapy, and six achieved complete remission (CR). Three of them subsequently relapsed. Seven patients were treated with all-trans-retinoic acid (ATRA), and four achieved CR through the differentiation of blasts into mature granulocytes. None has relapsed so far. CONCLUSIONS: Our findings suggest that tAPL is not exceptional, and usually has several features in common with other types of therapy-related AML with specific karyotype (ie, t(8;21),t(9;11), inv(16)): solid tumor rather than hematologic malignancy as primary tumor, short interval of development, absence of known preleukemic phase, prior chemotherapy with a combination of several drugs that often included an agent that targets topoisomerase II (doxorubicin or mitoxantrone, but less often VP16). Hematologic characteristics and response to therapy (intensive chemotherapy or ATRA) in tAPL do not seem to differ from those of de novo APL.