Context: Successful arterial cannulation requires wide and patent arterial lumen. A recent study has shown that success rate of radial arterial cannulation at first attempt is more at 45° angle of wrist extension in both young and elderly patients. No study has reasoned whether these high success rates at 45° is because of less compression of the radial artery at this particular angle of wrist extension. Hence, we attempted to study whether the radial artery dimensions changes with increasing angles of wrist extension in young, healthy female volunteers using ultrasound examination. Aim: To investigate the effect of increasing angle of wrist extension of 0, 15, 30, 45, 60, and 75° on radial artery dimensions at the level of the wrist joint using ultrasound examination. Settings and Design: A prospective single blinded study in volunteers. Subjects and Methods: Sonographic measurements of radial artery dimension at the wrist level were performed in 48 young, healthy female subjects. Height (anteroposterior in mm), width (mediolateral in mm) and depth (skin to artery) were measured at wrist extension of 0, 15, 30, 45, 60, and 75°. The dimensions at each angle are compared with 0° as the control and statistical analysis done. Statistical Analysis: One-way analysis of variance test. Results: No statistically significant change in dimension of the radial artery is observed with increasing angle of wrist extension. Conclusion: Ultrasound evaluation showed that increasing angle of wrist extension does not significantly change the dimensions of radial artery at the wrist joint level in young healthy female volunteers.