Abstract Femoral vein access is often required during resuscitation efforts and when other routes of intravenous access are difficult. This study evaluated by ultrasound the effect of abduction/external rotation of the hip on venous accessibility. This was a prospective repeated measurement study. The common femoral veins of 25 volunteers were scanned transversely inferior to the inguinal ligament with the leg straight and in external rotation/abduction. The diameter of the vein and percent accessible (not posterior to the femoral artery) were determined. Data were analyzed using repeated measures analysis of variance. The mean percentage of the femoral vein accessible with the leg in external rotation/abduction was greater than with the leg straight (82.6 ± 20.3 vs. 70.4 ± 26.3, respectively); p < 0.03. External rotation/abduction of the hip may improve the success rate of femoral vein cannulation by increasing the percentage of the femoral vein accessible.