The average annual age-adjusted incidence rate of multiple myeloma for Olmsted County, Minnesota, for 1965-77 was 2.7/10(5) person-years. The sex-specific rates for males and females were 3.5 and 2.2/10(5) person-years, respectively; the male-to-female incidence ratio was 1.6:1.0. These rates were similar to rates reported for white people from the Third National Cancer Survey and the New York and Connecticut tumor registries. This average incidence rate did not appear different from the rate for the 20-year period 1945-64 in Olmsted County. The incidence of multiple myeloma was not shown to have increased in the past 33 years, and the observed increase in mortality from this disease reported in other parts of the country indicated improved case ascertainment during recent years, a factor not likely to be important in Olmsted County.