PURPOSE: Knowledge of the normal in vivo distribution and variation of coronary ostial locations is essential in the planning of various interventional and surgical procedures. However, all studies to date have reported the distribution of coronary ostia locations only in cadaver hearts. In this study, we sought to assess the distribution of coronary ostial locations in patients using cardiac dual-source computed tomography (CT) and compare these values to those of human cadaveric specimens. METHODS: Measurements of the coronary ostia location were performed in 150 patients undergoing dual-source CT and in 75 cadavers using open measurement techniques. All 150 patients had a normal aortic valve function and no previous cardiac intervention or surgery. The location of the right and left coronary origin in relation to the aortic annulus and the height of the sinus of Valsalva were measured. RESULTS: Mean ostial locations at CT were 17.0 (+/-3.6) mm and 15.3 (+/-3.1) mm for the right and left coronary ostia, with large variations of both sides (right: 10.4-28.5 mm; left: 9.8-29.3 mm). In cadavers, mean locations were 14.9 (+/-4.3) mm [5-24 mm] for right and 16.0 (+/-3.6) mm [9-24 mm] for left coronary ostia. Comparison of CT and cadaver data showed statistically significant differences for right (P < 0.0001) but not left (P = 0.1675) coronary ostia. CONCLUSIONS: This study provides data of normal coronary ostial origins and demonstrates significant differences between in vivo and ex vivo measurements regarding the right coronary ostium. The observed large variations of coronary ostia origins emphasize the importance of considering such anatomic variations in the development of treatments.