During the 10-year period 1981-90, 1752 primary total hip arthroplasties (THAs) were performed in the county of south Jutland, Denmark. The annual number of THA increased until a steady state level was reached during 1988-90. The age and sex specific incidences were calculated for this period using the population distribution of the County. The age specific incidences were highest in the age-group 70-79 years for both female and males, namely respectively 485 and 410 THAs per 100,000 inhabitants. The overall incidence was 82 THA per 100,000 inhabitants. During the next 30 years, the demand for primary THA in Denmark is expected to increase 32 percent (from 4013 to 5307 THAs) as a consequence of demographic changes.