The total costs for patients who are sick-listed due to back and neck problems have not previously been determined prospectively on an individual basis. This study aimed to determine the total cost to a society, based on individually assessed costs of health services and loss of production in people who are sick-listed 28 days or more for back or neck problems. Detailed data on individuals' health-care consumption due to back or neck problems was collected through prospectively entered diaries and questionnaires, after 4 weeks, 3 months, 1 and 2 years, in a consecutively selected cohort of 1,822 employed persons aged between 18 and 59 years. Costs for health care and production losses due to work absenteeism were determined individually and combined to render total costs to society. The costs for all medical services during the 2-year study were 6.9% of total costs for back and neck problems. The single most expensive medical service was surgery. Transferred to a national level, annual total costs for back and neck problems corresponded to 1% of GNP. In conclusion, direct health-service costs were a small fraction of the total costs, consequently indirect costs offer the greatest potential for savings.