We performed a study of forty-three patients who had type-III osteogenesis imperfecta. Our purpose was to determine the frequency and severity of abdominal problems and the relationship between these problems and pelvic deformity. Twelve patients had had recurrent episodes of abdominal pain. Eleven of them had a history of chronic constipation, and five had been treated for fecal impaction. Radiographs had been made for ten of these patients, and eight of them had radiographic evidence of pelvic deformity with severe acetabular protrusion. Chronic constipation and recurrent abdominal pain are more frequent in patients who have osteogenesis imperfecta and acetabular protrusion than in those who do not have protrusion. These patients may benefit from early attention to a bowel program and referral to a gastrointestinal specialist.