A prospective study was made of 1500 elderly patients who suffered from acute hip fractures from 1986 to 1990. There were 36 per cent more fractures in the 6 colder months from November to April than in the rest of the year (P < 0.001). A strong correlation between the monthly adjusted fracture rate and the average lowest ambient temperature was also observed (P < 0.001). The fractures occurred in the older and less active patients during the 6 colder months. More importantly, they needed to wait longer for the operation during this 'high' season. This might be responsible for the higher medical complication rate after the operation. Better health care planning to help with the increased patient load in the 'high' season is essential to reduce the waiting time for the operation and the postoperative medical complication rate.