Arteriovenous fistulae (AVF) failure is the most common cause of morbidity and hospitalization in hemodialysis (HD) patients. The purpose of this study was to determine the effects of smoking and blood eosinophil count on the development of AVF thrombosis in HD patients. This cross-sectional study included 141 patients (M/F 80/61; age 43.4 +/- 11.6 years, HD duration 7.7 +/- 4.4 years). The following were analyzed as possible risk factors for AVF failure for all patients: demographic features, dialysis time, smoking, medications, body mass index, comorbid diseases, and various laboratory parameters (whole blood count and serum levels of albumin, calcium, phosphorus, uric acid, C-reactive protein, ferritin, and parathyroid hormone). AVF thrombosis was detected in 60 patients; in contrast, 81 patients had no thrombosis. Distributions of age, gender, and HD duration were similar between both groups. Univariate analysis showed that snuffbox AVF location (P < .0001), higher blood eosinophil count (P < .0001), smoking (P < .01), and higher hematocrit level (P < .05) were all associated with AVF thrombosis. According to multivariate analysis by logistic regression models, eosinophil count (RR = 1.005, P < .05) and snuffbox location (RR = 5.970, P < .05) were predictors of AVF thrombosis. When AVF location was excluded from the analysis, smoking (RR = 4.140, P < .01) and high blood eosinophil count (RR = 1.006, P < .005) were independent risk factors for thrombosis. Our study indicates that smoking and high blood eosinophil count may contribute to the development of AVF thrombosis.