Members of a religious isolate who live in approximately 240 farming colonies in the Canadian prairie provinces and the United States border states were studied. The sect's 6,700 members living in the province of Alberta, Canada, comprise more than 30% of this sect's population of North America. The numbers of their cancer cases ascertained from 1953 to 1974 in Alberta were compared to those expected from Alberta Cancer Registry rates. The overall incidence of registered cases of cancer among the religious isolate's females was significantly less than expected (48 observed, 74.2 expected), and in the males the overall incidence of cancer did not differ from that expected (52 observed, 56.5 expected). Significantly fewer cases of lung cancer than expected were found in males, and significantly fewer cases of carcinoma in situ of the cervix uteri were found in females. Finally, significantly higher incidence of stomach cancer was found in the sect's males. Data on a family with two cases of stomach cancer contributed to this observed excess of stomach cancer.