Pentasomy 8 as a sole anomaly in hematological disorders is rare. Only 2 such cases, one in acute monocytic leukemia and one in chronic myelomonocytic leukemia have been described in the literature to date. Here, we report the first case of a 42 year old man with erythroleukemia displaying a pentasomy 8 clone. Conventional cytogenetics of bone marrow cells showed 16 metaphases with pentasomy 8 and 9 with normal diploidy. Fluorescence in situ hybridization (FISH) analysis using a whole chromosome painting probe and a centromeric probe specific for chromosome 8 confirmed the presence of pentasomy 8 and also revealed a low percentage of a trisomic and a tetrasomic clone. The patient died three days after diagnosis without chemotherapy. The findings suggest that pentasomy 8 is associated with a heterogeneous group of myeloid disorders and probably plays a specific role in the progression of myeloid neoplasia.