The MEDOS study was a prospective, multicentre study of the incidence of hip fractures, carried out in six Mediterranean countries over a 12-month period (1988-1989). The majority of hip fractures recorded were extra-capsular and usually required a stable internal fixation to avoid instability and deformation or pseudoarthrosis. Surgery was performed in the majority of cases (85% of extra-capsular fractures and 84% of intra-capsular fractures), although this proportion also varied between centres. The type of operation performed depended on the type of fracture; the most common operation for intra-capsular fracture was hip replacement (67% of cases), while in extra-capsular fracture the most common intervention was stable fixation (50% of cases). Again, there were substantial differences between centres. During the period of hospitalisation, 26% of patients experienced minor complications, but only 2.4% experienced serious complications, with further surgery required in 2%. Mortality during hospitalisation was 5.1% overall (4.8% and 5.7% in intra- and extra-capsular fracture cases, respectively). The average duration of hospital stay was 24 days, but this varied between centres, with a tendency for shorter stays to be associated with a greater proportion of cases treated surgically.