The role of exercise in the treatment of cystic fibrosis has received increasing attention over the past 15 to 20 years. As a group, physical fitness is reduced for people with cystic fibrosis, although tremendous individual variability exists. Limitations in exercise performance appear related to the extent of lung disease and compromised nutritional status. Exercise testing with subsequent development of individualised exercise programmes offers this unique population an opportunity to attain the well-recognised benefits of exercise.