Some cases of acute myeloid leukemia following organ transplant (PT-AML) have been published in the literature. We report the second case of acute promyelocytic leukemia (APL), which developed post-transplant and immunosuppressive treatment, in a 50-year-old male who had undergone a renal transplant. At diagnosis he presented typical t(15;17)(q12;q13) with additional abnormalities, including +8,t(13;22)(q12;q13) and an abnormal chromosome 1 which was better characterized by fluorescence in situ hybridization (FISH). He obtained cytological, karyotypic and molecular complete remission (CR) with induction treatment according to the all-trans retinoic acid + idarubican (AIDA) protocol; after 12 months, he relapsed (molecular relapse) and achieved molecular remission with all-trans retinoic acid (ATRA) plus mitoxantrone and cytosine arabinoside. After a further 14 months, he was treated with arsenic trioxide for cytological relapse and obtained a third CR; at the cytological relapse the karyotype showed 47,XY,+8, t(15;17)(q22;q21),t(13;22)(q12;q13),der(22)t(1;22)(p22;q13). He is alive 3.3 years after diagnosis of APL. Cyclosporin A (CsA) was given during all cycles of chemotherapy. We did not observe any severe infections or kidney failure during treatments. The use of conventional cytogenetic analysis plus FISH may identify complex karyotype also in transplanted patients receiving immunotherapy, and may also contribute to a better assessment of PT-AL.