The conus coronary artery has been reported to arise independently from the aorta in approximately 45 per cent of hearts. In this study, 305 necropsy specimens were examined to determine the origin of the conus coronary artery and variations in patterns of origin with respect to age. Three patterns were recognised: 1, in which the conus artery arose from the aorta independently of the right coronary artery; 2, in which the conus artery and the right coronary arose from a common ostium; and 3, in which only the right coronary artery took origin from the right aortic sinus. The relative incidence of the three patterns varied with age. Pattern 1 was recognised in 14 to 24 per cent of specimens from patients under the age of 2 years, whereas in older patients, it occurred in 41 to 63 per cent. These data suggest that aortic origin of the conus arterial ostium may appear in some individuals between 2 and 4 years of age, and they support the concept that some coronary arterial patterns are not fully established at the time of birth.