Aims and objectives: Transradial interventions are gaining popularity in recent years. However the radial artery being small, there is a limitation in using interventional devices through this route. We have measured radial and ulnar arteries size in adult patients at our tertiary care cardiology center in southern Rajasthan. Method: Adult patients >30 years, who came for Echocardiography at a tertiary care center were included. Radial and ulnar arteries inner diameters were measured 2–3 cm above the Styloid process in both forearms with the Ultrasonography. Patient information about weight, height, diabetes and hypertension were collected. Body mass index and Body surface area were calculated. Results: We studied 204 patients, which includes 60.8% males. Mean diameter was 2.325 ± 0.4 mm mm for radial arteries and 2.358 ± 0.39 mm for ulnar arteries (p = 0.24). Hypertensive and male patients had larger mean radial artery diameter than non hypertensive (2.383 mm v/s 2.272 mm, p = 0.006) and female patients (2.37 mm v/s 2.26 mm, p = 0.008) respectively. Diabetic patients (2.305 mm) had nonsignificantly smaller radial arteries diameters than nondiabetics (2.329 mm, p = 0.6). We calculated correlations between radial arteries diameters and Body surface area, Body mass index, height and weight of patients, none of these correlations were statistically significant (r = 0.30, r = 0.28, r = 0.07, r = 0.031 respectively). Conclusion: Mean radial artery diameter (2.325 ± 0.4 mm) in the study was slightly smaller than ulnar artery (2.358 ± 0.39 mm). Males and hypertensives had a larger mean radial artery diameter than females and non hypertensives. Radial artery inner diameter measurement by Ultrasonography may be more helpful than Allen's test for ideal selection of cases.