We studied retrospectively 90 Chiari osteotomies in 83 adults with pain, hip dysplasia and arthrosis. At follow-up after 6 (2-15) years, 35 hips were pain-free, 38 had rare or slight pain, and 17 had moderate or severe pain. The dysplastic acetabulum was corrected in all but 5 cases. There was diminution of arthrosis in 36 hips, no change in 38, and worsening in 16 hips. Functional outcome was best when surgery was performed before the age of 40, and in hips with the greatest degree of dysplasia. However, two thirds of the patients aged over 40 years at surgery had a good result.