The cost and time of hospitalization were analysed for 4161 hip fractures in 3898 patients aged 40 years or over treated in a Danish municipality from 1970 to 1985. The mean hospitalization time decreased from 32 to 21 days (P < 0.0005). This tendency was most pronounced for patients who were treated with osteosynthesis. However, the annual number of fractures increased from 134 to 367. Consequently, the bed use rose 79 per cent. As the number of hip fractures is predicted to increase further, the total number of bed-days required by these patients will probably also continue to increase. In addition, the standard expense per day for a hospitalized orthopaedic patient increased from 372 to 2982 DKK. Thus, the mean expense per patient was 12 000 DKK in 1970 versus 63 000 in 1985, i.e. the total expense increased 1433 per cent. After adjustment for price indexes the increase was 362 per cent. The total cost of acute hospital care of hip fractures in Denmark was estimated to be > 0.5 billion DKK in 1985.