Dramatic increases in mortality from multiple myeloma have been reported in the United States and the United Kingdom over the past three decades. To assess what fraction of this increase, if any, might be attributable to a change in the incidence of this disease, we examined the incidence of multiple myeloma during 1950 to 1979 in Malmö, Sweden, a city chosen because of its medical community's longstanding interest in this disease. The average annual incidence rates per 100,000 population were 4.9 for males and 3.7 for females (adjusted to the European age-standardized population). These rates are among the highest in the world. Unlike secular trends for myeloma in the United States and the United Kingdom, where large increases in mortality rates have been reported, the rates in Malmö have increased only slightly, and the increase was restricted to males, suggesting the possibility of environmental causes. We suggest that the rates in Malmö may represent the asymptote of myeloma's incidence that will be approached in other white populations as case ascertainment among them becomes complete.