Hip fracture is a global and a growing public health problem. More women than men sustain hip fractures, the incidence increases exponentially with age and mean age is above 80. About one third of hip-fracture patients suffer from dementia and are prone to develop acute confusional state (delirium). Delirium is one of the most common complications after hip-fracture surgery, and seriously impacts on morbidity and mortality. Malnutrition is also common in hip-fracture patients and is associated with postoperative complications, such as delayed healing of the wound, infections and decubitus ulcers. Arthroplasty is usually preferred procedure in displaced femoral neck fractures but is, however, controversial in patients with dementia due to the fear of dislocation of the prosthesis. The aims of this thesis are to identify risk factors for delirium and the impact of delirium on rehabilitation outcome, to evaluate whether a postoperative multi-factorial intervention program could reduce delirium, to investigate the effect of a nutritional intervention and to evaluate complications, functional outcome and mortality regarding two surgical methods, hemiarthroplasty (HAP) and internal fixation (IF), in old patients with femoral neck fracture. Thirty-eight out of 61 consecutive patients (62%) were delirious on admission to hospital or developed postoperative delirium. An increased risk of postoperative delirium was found among hip-fracture patients with dementia and/or depression. Delirious patients were hospitalized longer, were more dependent in their activities of daily living, had poorer psychological well-being and suffered more complications than non-delirious patients. A postoperative multi-factorial and multidisciplinary intervention program reduced the incidence, at 55% vs 75% (p=0.003), and number of days with delirium, 5 vs 10 days (p=0.009). Postoperative complications were also reduced; decubitus ulcers 9% vs 22% (p= 0.010), urinary tract infections 31% vs 51% (p=0.005), falls 12% vs 27% (p=0.007), and the mean hospitalization period was 10 days shorter in the intervention group (p=0.030). Malnutrition was common among all these patients (53 %) and associated with postoperative complications such as decubitus ulcers and delirium. However, the nutritional intervention had no effect on nutritional parameters at four months, nevertheless men had better nutritional outcomes than women. A higher proportion of patients with dementia operated on using HAP had regained their pre-fracture ability to walk independently at the one-year follow up compared with those operated on using IF. Six of 83 patients dislocated their HAP during hospitalization and during an episode of delirium, none had dementia. No difference in mortality between the surgical methods was seen. Dementia per se should not be a reason to disqualify patients from being treated with the most appropriate surgical method. It is clinically important to discriminate between dementia and delirium, since delirium can be prevented and treated even in patients with dementia. Old patients undergoing surgery have special needs that are not always catered for in ordinary orthopaedic or surgical wards. The special care for these patients should include: a combined nursing and medical care based on comprehensive geriatric assessments, systematic prevention, detection and treatment of postoperative complications such as delirium, hypoxemia, urinary tract infections, pain, malnutrition and an active rehabilitation. It is obvious that improved quality of care reduces patient suffering and seemingly the costs for society.