Vascular access thrombosis is more common with polytetrafluoroethylene (PTFE) grafts than with native arteriovenous fistulae (AVF). Recent studies report an unexplained excess vascular access morbidity in women on hemodialysis. We studied 92 consecutive end-stage renal disease (ESRD) patients receiving their first permanent hemodialysis vascular access at initiation of hemodialysis to identify variables that determine assignment of either a PTFE graft or a native AVF. Independent variables included: age, gender, race, etiology of ESRD, and whether or not access surgery was electively planned before need for dialytic therapy. The 51 women and 41 men included 65 blacks, 13 Hispanics, 11 whites, and 3 Orientals aged 50 +/- (SD) 16 years. Of the 92 subjects, 54 (59%) received an AVF, while 38 (41%) received a PTFE graft. 36 (94%) of 38 PTFE grafts were placed in the upper arm as compared with 9 (17%) of 54 AVF (p = 0.0001). Also, 45 (83%) of 54 AVF were placed in the forearm as compared with only 2 (6%) of 38 PTFE grafts (p = 0.0001). Women were more likely to receive a PTFE graft - 28 (55%) of 51 - than men - 10 (24%) of 41 (p = 0.003). By contrast, men were more likely to get an AVF - 31 (76%) of 41 - than women - 23 (45 %) of 51 (p = 0.003). The log linear analysis confirmed that this finding was significant (p = 0.0018) for the coefficient of interaction between gender and type of vascular access. No other independent variable had a significant relationship with type of vascular access. We conclude that women with ESRD are more likely to receive a PTFE graft for hemodialysis, while men are more likely to get an AVF. These findings may explain, in part, the reported excess vascular access morbidity in women on hemodialysis.