The purpose of this study was to analyse the complications of THAs in CDH. 418 THAs were performed in 356 patients, with a mean follow-up 108 (7–237) months. The mean age was 53.3 (24–79) years. 83 patients had CDH in high position. 40 stems were custom made. Complications included seven intraoperative fractures of the femur, 12 dislocations, four peroneal nerve palsies that recovered, 25 heterotopic ossifications, seven deep vein thromboses, three pulmonary embolisms, early mechanical loosening in four cemented and ten cementless cups and three infections. Complications were diminished dramatically last years due to improved surgical technique, new available implants and preoperative evaluation of the hip with CT and CAD-CAM-CAE study.