OBJECTIVE To establish the result of treatment of medial femoral neck fractures in patients aged 70 years and older using Hansson pins introduced percutaneously. METHODS Descriptive. METHODS Department of Surgery, University Hospital Utrecht, the Netherlands. METHODS Ninety-two patients aged 70 years and older with a medial femoral neck fracture were treated in the period 1986-1994 with osteosynthesis using Hansson pins. The case histories and X-rays of these patients were analysed. All fractures were classified according to Garden and Pauwels, with Singh classification of bone quality. The result of the operation was evaluated with the aid of postoperative X-rays. RESULTS The patients' mean age was 80 years. There were 16 non-dislocated Garden grades I or II and 71 dislocated Garden III and IV fractures. Four patients died within 30 days after the operation. At the time of the follow-up (after an average of 4.5 years), 45 patients had died. Thirty-three patients in all developed a fracture-related complication; 27 of them underwent reoperations during which 19 (21%) were fitted with a head-neck prosthesis or a total hip prosthesis. All reoperations which included implantation of a prosthesis were performed in dislocated Garden grades III and IV fractures. In fractures of this type in which postoperative repositioning proved inadequate, more reoperations were performed than in the Garden grades III and IV fractures with correct posture. CONCLUSIONS Treatment of a medial femoral neck fracture in elderly patients by means of internal fixation with percutaneously introduced Hansson pins gives results similar to those of other types of internal fixation. This is a good operation for Garden grades I and II fractures, whereas in Garden grades III and IV fractures in which repositioning is impossible, internal fixation should be refrained from and a head-neck prosthesis should be implanted in one session.