Native arteriovenous fistula is considered the best type of access for dialysis. Its function is affected by multiple factors.The aim of the study was to identify risk factors of the loss of fistula patency.Material and methods. Between 1990-2004, 218 patients underwent 276 surgical procedures involving vascular access creation. In 245 (89%) of cases, a fistula was created using only patient's own blood vessels; in 31 (11%) of cases a vascular graft was implanted. 158 (64%) radio-cephalic fistulae were created, 15 (6%) radiobasilic fistulae, 33 (14%) brachiocephalic and 39 (16%) brachiobasilic fistulae. Duration of primary patency was identified for 217 native fistulae. Age, gender, diabetes mellitus, type, mode of creation and fistula location, vein translocation, type of anastomosis and time of initial cannulation were analyzed as potential factors affecting the fistula patency. Cox proportional hazards model was used in the analysis.Results. Probability of fistula patency loss in patients above 46 years of age was 2.12-fold higher than in younger patients and 1.62-fold higher for end-to-side anastomosis versus end-to-end anastomosis. Risk of loss of patency in fistulae cannulated for the first time within the first 14 days, 15-21 days and 22-35 days from their creation was 31-, 19- and 7-fold higher than when they were cannulated after the first 35 days.Conclusions. Type of vascular anastomosis, age above 46 years and time of the first cannulation are independent risk factors of the loss of patency of vascular access. First cannulation should not take place earlier than 7 weeks after its creation.