Objective: To investigate the incidence of JAK2V617F gene point mutation in patients with myeloproliferatives diseases (MPD) and its clinical significance. Methods: Genomic DNA from bone marrow and peripheral blood cells were extracted from 68 patients with MPD.Allele specific polymerase chain reaction was used to amplify the exon 12 of JAK2 gene which harbours V617F mutation.The PCR products were identified by DNA sequencing.JAK2V617F gene point mutation and its impact on peripheral blood cells were analyzed. Results: The incidence of JAK2V617F mutation in 68 patients with MPD was 65.28;.The positive rate of JAK2V617F point mutation was 77.77; in patients with PV (36/59),56.52; in patients with ET (23/59) and 44.44; in patients with IMF (4/9).In all groups,the incidence of JAK2V617F point mutation in bone marrow and peripheral blood were equal.Patients with JAK2V617F mutation in PV group had higher counts of white blood cell and hemoglobin in peripheral blood than patients without JAK2V617F point mutation (P＜0.05).Patients with JAK2V617F mutation in ET group had higher counts of white blood cell than those without JAK2V617F mutation (P＜0.05); there was no significant difference in platelet count. Conclusion: JAK2V617F point mutation can affect the hematologic features,which may be of diagnostic value for MDP with negative BCR-ABL gene.