Relapse after anthracycline based combination chemotherapy is frequently seen in patients with aggressive non Hodgkin's Lymphomas (NHL), whereas complications such as secondary leukemia or solid tumor rarely occur. We report a patient with diffuse large cell (DLC) NHL and concurrent renal cancer, who developed acute myelofibrosis (AMF) later in the course of her disease. This 60-year-old female patient presented with pancytopenia and a right sided renal mass. Diagnostic work up revealed severe bone marrow infiltration by DLC NHL and renal cancer T1N0M0G2. Cytogenetic and molecular evaluation of bone marow cells showed three distinct clones, (a normal 46XX karyotype, a ringed chromosome 7 and a third clone with an enlarged chromosome 2 as well as several fragments). The patient underwent nephrectomy and eventually received 6 cycles of CHOP 14 chemotherapy. Anemia persisted followed by severe granulocytopenia and thrombocytopenia 6 weeks later. Repeated bone marrow biopsy showed absence of lymphoma and/or cancer metastasis, but massive myelofibrosis with an increased number of atypical megakaryocytes. Considering the short clinical course and the absence of hepatosplenomegaly AMF was diagnosed. The concurrence of three distinctneoplasms within a short period of time as well as the complex cytogenetic aberrations found in her bone marrow cells reflect a strong individual susceptibility to malignant disease in this patient.