Twenty five patients (twenty seven hips) who had Chiari osteotomy at Kang Nam St. Marys Hospital between 1980 and 1995 were reviewed to evaluate the factors in the operative technique that contribute to successful outcome and assess the clinical results in various conditions. The length of follow-up ranged from one to fourteen years and the age of at operation ranged from four to twentythree years. Eighteen patients had developmental dysplasia of the hip: four, septic hip: three had another disorders, Prior to the Chiari osteotomy, fourteen hips had an femoral osteotomy and four, trochanteric arthroplasty. We used to the standard osteotomy as described by Chiari with certain modification. A pneumatic saw and osteotome are used instead of Gigli saw. This technique is simple procedure to make the correct level and angle. Bone graft was not performed in all cases even the osteotomy was displaced more than 50 percent of the iliac width. The overall results were 12 excellent, eight good, five fair, and two poor. In eleven patients, the osteotomy had to be displaced more than 50 percent to provide good coverage of the femoral head. Their results were good or excellent. A good result will be obtained if enough attention is paid to displacing the osteotomy. The osteotomy using the pneumatic saw provides accurate level and direction of osteotomy and it is an simple procedure also.