Introduction: Chronic myeloproliferative disorders (CMPD) are chronic myeloid hematological disorders, characterized by increased myeloid cell proliferation and fibrosis. Impaired apoptotic mechanisms, increased cell proliferation, uncontrolled hematopoietic cell proliferation and myeloaccumulation may contribute to the pathogenesis of CMPD. The aim of our study was to show the possible role of FAS/FASL gene polymorphisms in CMPD pathogenesis and investigate the association with clinical parameters and susceptibility to disease. Material and methods: We included 101 (34 polycythemia vera (PV), 23 primary myelofibrosis (PMF), 44 essential thrombocythemia (ET)) CMPD patients diagnosed according to the WHO classification criteria and 95 healthy controls in this study. All the patients and the controls were investigated for FAS/FASL gene expression, allele frequencies and phenotype features, and also FAS mRNA levels were analyzed. Results: Chronic myeloproliferative disorders patients showed increased FAS-670AG + GG genotype distribution compared with the control group (pG gene polymorphism and some clinical parameters such as splenomegaly and thrombosis (p >0.05). No statistically significant difference in FASL+843C>T genotype or allele frequency was found between groups (p >0.05). Moreover, no statistically significant difference was detected in FASL and JAK2V617F mutations (p >0.05). FAS mRNA expression was 1.5-fold reduced in patients compared to healthy subjects. Conclusions: According to our findings, FAS/FASL gene expression may contribute to the molecular and immunological pathogenesis of CMPD. More investigations are needed to support these data.