Cystic fibrosis (CF) is the most common life-shortening inherited disease of the Caucasian race, with a prevalence of around 1 in 2500 live births. Advances in the treatment and management of respiratory and pancreatic disorders have dramatically increased the life expectancy of patients with CF. This article presents an overview of cost-of-illness studies of CF, identifies deficits in the available health economic analyses of CF and discusses which specific factors are essential for the economic evaluation of potential therapies, based on a critical review of the health economic literature on two main therapeutic strategies. Cost-of-illness studies of CF have predominantly been restricted to direct costs. According to the literature, direct costs amount to between 6200- 16300 US dollars (1996 values) per patient per year. As most studies likely underestimated the actual costs (e.g. by disregarding provision of certain healthcare services), real healthcare costs tend to be at the upper end of the cost range. Healthcare costs depend on the patient's age (for adults, costs are approximately twice as high as for children), the grade of severity (the cost relationship of severe to mild CF is between 4.5 and 7.1) and other factors. Lifetime direct costs of CF are estimated at 200 000-300000 US dollars (at 1996 values and a discount rate of 5%). Home intravenous (IV) antibacterial therapy and recombinant human DNase (rhDNase; dornase alfa) treatment are the two main therapeutic strategies most often evaluated in health economic studies of CF. While home IV antibacterial therapy (compared with inpatient IV antibacterial therapy) is assumed to be cost saving, rhDNase treatment is a very cost-intensive therapy intended to efficiently achieve health improvements. Health economic analyses of future CF therapeutic technologies should present explicit data regarding healthcare services provision, resource consumption and unit costs. Indirect costs and patient costs should be considered more often than they have to date, particularly when they are significantly influenced by novel CF technologies. The perspective of health economic studies should be stated explicitly and always include the societal perspective. More economic studies should be based on a controlled, and preferably randomised, design. The observation period must be long enough to identify long-term effects of interventions. A greater number of effectiveness studies should be performed to determine costs and outcomes of therapies applied under everyday life conditions for patients with CF. Finally, international comparison studies should identify the influence of different healthcare systems on the costs and outcomes of interventions.