A prospective, randomized clinical study has been performed on 104 patients with an acute femoral neck fracture, comparing internal fixation (von Bahr screws) with primary prosthetic replacement (Christiansen endoprosthesis). Immediate weight bearing was allowed in both groups. The postoperative mortality rate was similar in the two groups. Internal fixation proved to be a less time-consuming operation, gave a shorter hospitalization time and was associated with a significantly reduced morbidity rate compared with prosthetic replacement. No blood transfusion was needed in the internal fixation group. Primary prosthetic replacement was associated with earlier postoperative mobilization, probably gave a more definitive treatment with fewer reoperations, and showed better results at 1-year follow-up.