One thousand fourteen consecutive large intestines were removed at autopsy from persons over the age of 14 years and examined for diverticular disease. Diverticulosis was encountered in 194 patients (19 percent). The lesion appeared early in life, after the second decade. Men were affected more frequently than women before the age of 60 years. Chinese men had significantly more diverticular disease than Malayan men (P less than 0.01) and Indian men (P less than 0.02). Chinese men also had significantly more diverticular disease than Chinese women. There was a predominance of right colon involvement, with the disease affecting especially the ascending colon and cecum. This pattern was observed in all three major ethnic groups, and in both the Singapore-born and foreign-born Singaporeans. The cause of right-sided diverticulosis is unknown. It appears that, while adoption of the western diet may influence the prevalence of diverticular disease, the site of predilection is determined more by racial or genetic predisposition. All diverticula examined histologically were false, including 39 (20 percent) solitary diverticula. The distribution of solitary diverticula was similar to that of multiple diverticulosis. It is suggested that solitary and multiple diverticulosis are part of the spectrum of the same disease.