Background: This study aims to define normal coronary arterydiameters of males and females in a sample of Turkish population,compared to Asian-Indian and Western Caucasian populations.Methods: Angiographic and demographic data of a total of 324patients (147 males, 177 females; mean age 55.3±10.1 years; range,32 to 82 years) who underwent elective coronary angiography withangiographically normal coronary arteries between July 2017 andMarch 2019 were analyzed retrospectively. Proximal diametersof major epicardial coronary arteries were measured using theAxiom Artis software according to edge detection method. All themeasurements were adjusted to the body surface area. Unadjustedand adjusted values were compared between genders and with theAsian-Indian and Caucasian population samples.Results: The mean diameters of unadjusted/adjusted left maincoronary artery, proximal left anterior descending artery, proximalleft circumflex artery, and proximal right coronary artery were4.5±0.6 mm/2.4±0.4 mm/m2, 3.7±0.5 mm/1.9±0.3 mm/m2,3.3±0.6 mm/1.7±0.3 mm/m2, and 3.4±0.6 mm/1.8±0.4 mm/m2,respectively. Adjusted left main coronary artery and proximal leftcircumflex artery were narrower, and unadjusted proximal leftanterior descending artery and unadjusted/adjusted proximal rightcoronary artery were larger in men, compared to women in theTurkish population. Turkish population had similar body surfacearea and unadjusted/adjusted coronary diameters with Caucasians,whereas adjusted proximal left anterior descending artery was largerin the Turkish population than in Asian-Indians.Conclusion: Our study findings on the Turkish populationcontradict the traditional belief that women have narrowercoronary arteries then men. Furthermore, the Turkish populationhave comparable adjusted/unadjusted coronary diameters withthe Western Caucasians, but larger adjusted/unadjusted proximalleft anterior descending artery, compared to Asian-Indians. Webelieve that our findings may contribute to the global data pool ofnormal coronary diameters and can be utilized in future studies asa database.