Coronary artery disease (CAD) rates are higher in Asian-Indians than in Caucasians. CAD occurs at an earlier age in this group, with about a quarter of all myocardial infarctions occurring under the age of 40. Previous reports have suggested smaller coronary artery size in Asian-Indians as a major cause for increased CAD in this population. This study sought to evaluate the size of normal “atheroma-free” segments of the epicardial coronary arteries in Asian-Indians and Caucasians aged ≤40 years undergoing coronary artery intervention in other diseased segments. A total of 69 consecutive patients (41 whites, 28 Asian-Indians) aged ≤40 years were evaluated. Angiograms were analyzed using standard quality control analysis software with digital acquisition. The arteries measured were the left main, left anterior descending, left circumflex, and the right coronary artery. Conventional risk factors, including hypertension, smoking, and diabetes, that could influence coronary size were also assessed. The coronary arteries of Asian-Indian patients showed significantly smaller values in the mean diameters of the left main (2.96 mm vs 4.04 mm, p = 0.0004), left anterior descending (2.48 mm vs 3.24 mm, p = 0.0005), left circumflex (2.52 mm vs 3.06 mm, p = 0.00002), and right coronary artery (2.71 mm vs 3.65 mm, p = 0.0008) as compared with Caucasians. Even after correction for body surface area, a statistically significant difference remained in coronary artery diameters. In conclusion, statistically significant difference in the mean diameter size even after correction for body surface area in Asian-Indians has implications for predisposition to atherosclerosis, and more challenging performance of procedures such as coronary artery bypass grafting, stent implantation, or atherectomy.