Background: A single nucleotide polymorphism (T > C) rs2070744 due to transition of a thymine to a cytosine at T-786C in the promoter region of eNOS was found to reduce the rate of mRNA transcription by 50%, resulting in decreased serum NO levels which can inhibit apoptosis or stimulate tumor proliferation, angiogenesis and metastasis. Objective: To evaluate the association between Nitric Oxide Synthase gene T-786C polymorphism and Polycythemia Vera patients in Sudan. Material and Methods: A total of 40 patients with Polycythemia Vera and 50 control subjects were enrolled this study. DAN extrication samples previously extracted from EDTA Blood collected from SPV and store at- 20C. Analysis of the eNOS¬786T > C promoter polymorphism were carried out by allele ¬specific polymerase chain reaction method (PCR). Results: The present study reported that, molecular analysis showed that, the most frequent genotype in patients was TT 65% (26) followed by TC genotype 25% (10) and the reaming frequency was CC 10% (4) .While in the control group there was 100% TT genotype. Conclusion: No significant difference was found between the distribution of the eNOS¬786T > C genotype in PV patients and the general population in Sudan.