We studied the health care consumption and costs after a hip fracture in 1,060 and 1,178 elderly patients admitted from their own home before and after the implementation of a prospective payment system in Stockholm. The total number of bed-days was estimated by merging the inpatient database and the municipal records of living accommodations for the elderly. By using a detailed patient-related accounting system and separating cost for surgery and "hotel" cost, we could compare costs in different types of rehabilitation. After the change in reimbursement system, the orthopedic stay was almost halved from 20 to 12 days. This was achieved by earlier and increased discharge to geriatric wards, where bed-day consumption doubled (107%), so that the total cost actually increased by 12%. This is not readily apparent from the official heath care statistics, which depict a more favorable cost development, as diagnosis-related registration for a large part of the geriatric care is no longer included. In contrast, a rehabilitation program in one of the acute hospitals, emphasizing continuity in the postoperative phase, reduced the total cost for treatment and rehabilitation by 12%. A prospective reimbursement aiming at reducing the costs of acute care does not necessarily result in overall savings.