PURPOSE: To compare various objective ultrasonographic (US) criteria for native arteriovenous fistula (AVF) maturation with subsequent fistula outcomes and clinical evaluation by experienced dialysis nurses. MATERIALS AND METHODS: US fistula evaluation results were analyzed retrospectively in 69 patients within 4 months after AVF placement; adequacy for dialysis was known in 54. Measurements included minimum venous diameter and blood flow rate. Experienced dialysis nurses examined 30 fistulas clinically. Predictors of fistula adequacy were analyzed with univariate and multivariate logistic regression. Mean fistula diameters and blood flow rates were compared by using analysis of variance or unpaired Student t tests. RESULTS: Fistula adequacy for dialysis doubled if the minimum venous diameter was 0.4 cm or greater (89% [24 of 27]) versus less than 0.4 cm (44% [12 of 27]; P <.001). Fistula adequacy for dialysis was nearly doubled if flow volume was 500 mL/min or greater (84% [26 of 31]) versus less than 500 mL/min (43% [nine of 21]; P =.002). Combining venous diameter and flow volume increased fistula adequacy predictive value: minimum venous diameter of 0.4 cm or greater and flow volume of 500 mL/min or greater (95% [19 of 20]) versus neither criterion met (33% [five of 15]; P =.002). Women were less likely to have an adequate fistula diameter of 0.4 cm or greater: 40% (12 of 30) of women versus 69% (27 of 39; P =.015) of men. No significant differences in blood flow or minimum venous diameter were found during 2-4 postoperative months. Experienced dialysis nurses' accuracy in predicting eventual fistula maturity was 80% (24 of 30). CONCLUSION: US measurements of AVF at 2-4 months in patients undergoing hemodialysis are highly predictive of fistula maturation and adequacy for dialysis.