For the 30 years from 1950 through 1979, the population of Rochester, Minnesota, averaged 45,800, resulting in almost 1.4 million person-years of observation. During that time, 11 cases of pheochromocytoma were diagnosed in this population; thus, the average annual incidence rate was 0.8 per 100,000 person-years. With the inclusion of two additional diagnosed familial cases, the incidence rate would be 0.95 per 100,000 person-years. Five of the 11 cases were diagnosed initially at autopsy.