The incidence of carpal tunnel syndrome in the population of Rochester, Minnesota, from 1961 through 1980 was determined by use of the medical records-linkage system of the Rochester Epidemiology Program Project at the Mayo Clinic; 1,016 patients (1,600 affected hands) were identified. Incidence (cases per 100,000 person-years) was 99 (crude) overall, whereas the age-adjusted rates were 52 for the men, 149 for the women, and 105 for both sexes combined. Age-adjusted incidence rates increased from 88 during the 1961 to 1965 quinquennium to 125 during the 1976 to 1980 quinquennium; these rates probably reflect better recognition rather than a true increase in incidence rates. Age-specific rates generally increased with age in men, whereas in women a peak was reached in the 45 to 54 age group.