The purpose of this study was to examine children and adolescents with cystic fibrosis for an increased frequency of fracture and excessive thoracic kyphosis, which may result from inadequate skeletal mineralization. In a survey of 143 patients (ages 4.7 to 21.9 years; mean, 11.3 years), the fracture rate for male patients from birth to 5 years of age was higher than for female patients and both rates were comparable with those for normal children. In contrast, female patients 6 to 16 years of age with cystic fibrosis had a higher-than-normal fracture rate and a higher rate than their male counterparts. Review of the chest radiographs showed that thoracic kyphosis correlated with age and with disease severity as judged by Brasfield scoring. In the > 15-year-old age group, kyphosis exceeding 40 degrees, the upper limit of normal, was found in 77% of the female patients and 36% of the male patients. The cause of these findings is uncertain and perhaps multifactorial, but osteopenia is likely a contributing factor. As the life expectancy of patients with cystic fibrosis continues to increase, the skeletal consequences, particularly in female patients, may become increasingly significant.