The purpose of the present study was to determine the incidence of musculoskeletal injuries among professional ballet dancers in the Norwegian National Ballet. A 19 weeks prospective study with registration and clinical assessment of dancers with injuries was conducted. Medical staff working for the National Ballet registered incidence of injuries. In addition the dancers filled out a questionnaire about previous injuries, their work situation, and factors they believed increased the risk of injuries. Of the 41 dancers (80% response rate), 31 dancers experienced one injury or more. The majority of injuries involved foot and ankle. Twenty-two per cent of the injuries were acute injuries. Seventy-five per cent of the injuries were soft tissue injuries. Most injuries were of mild to moderate severity. Sixteen per cent of the injuries resulted in absence from work. Factors, the dancers believed were associated with risk of injuries were related to training, organizational factors and environmental factors. Seventy-eight per cent of the dancers experienced "negative" stress at work. Sixty-four per cent experienced that they had little influence on their work conditions. This study showed, however, no significant association between these psychological factors and musculoskeletal injuries. It is concluded that there is a high incidence of musculoskeletal injuries in the Norwegian National Ballet.