In chronic myeloid leukemia (CML) proliferation is increased and resistance to apoptosis has been proposed as a mechanism accounting for myeloid cell expansion. There is still controversy on whether apoptosis plays an important role in the regulation of myelopoiesis. This study aims to investigate whether apoptosis-related proteins play a role in the evolution of CML and to identify, the relationship between Fas, p53 and apoptosis protease activating factor (Apaf-1) in CML. We found increased p53 and Apaf-1 messenger ribonucleic acid (mRNA) in patients with CML. However, one patient, who had a p53 point mutation, showed a massive elevation of p53 mRNA during blast crisis yet, conversely, a considerable reduction in Apaf-1 mRNA and Fas mRNA. Our results show an in-vivo linkage between Fas, p53 and Apaf-1 transcription regulation. This suggests that key genes involved in apoptosis are also involved in CML disease progression.