ObjectiveTo investigate the value of cementless total hip arthroplasty (THA) for the treatment of Crowe type Ⅲ developmental dysplasia of hip (DDH) in adults. MethodsBetween September 2013 and September 2015, 50 patients (51 hips) with Crowe type Ⅲ DDH were treated. There were 20 males (20 hips) and 30 females (31 hips), with the average age of 39 years (range, 19-55 years). The left side was involved in 34 cases, the right side in 15 cases, and both sides in 1 case. All patients had the symptoms of limp walking and hip pain. The disease duration was 10-47 months (mean, 26 months). The sign of "4" number test and Trendenleburg sign were positive; the Harris score was 38.9±7.1. The bilateral lower extremities discrepancy was 2.5-4.0 cm (mean, 3.3 cm) before operation. All the patients underwent cementless THA, and acetabulum by structural femoral head autograft was performed in 28 cases (28 hips). ResultsAfter operation, the incision healed by first intention. Only 2 patients (2 hips) had femoral nerve palsy, and 7 patients (7 hips) had leg swelling, which were cured after symptomatic treatment. All the patients were followed up 6-18 months (mean, 10 months). The sign of limp walking was improved after operation, hip pain was relieved in 46 patients (46 hips) and only 4 patients (5 hips) still had mild pain. The X-ray films showed bony healing at 3-6 months (mean, 5 months) after operation. At last follow-up, the patients had equal limb length with the discrepancy less than 1 cm (mean, 0.4 cm). At last follow-up, the Harris score was significantly increased to 91.2±2.8 (t=-79.77, P=0.00). ConclusionThe cementless THA is an effective method to treat Crowe type Ⅲ DDH in adults.