We report here a case of acute nonlymphocytic leukemia evolving from a myelodysplastic syndrome which developed in an elderly man who had received radiation therapy for a prior cancer. Cytogenetic analysis revealed the following karyotype: 47,XY, + 8,t(1;6)(p13;p23). The breakpoints in the translocation are in the regions of the NRAS1 and PIM1 oncogenes on chromosomes 1 and 6, respectively. This translocation has not been previously observed in hematological malignancies.