The aims of this study were to estimate the incidence of acute confusional state (ACS), its predisposing factors and consequences in 111 consecutive patients operated for fractured neck of the femur. The incidence of ACS was 61 percent and the predicting factors were old age and dementia. Drugs with anticholinergic effect, depression, and previous stroke were factors that seemed to be associated with the development of ACS. Ninety-two percent of the patients who had severe perioperative blood pressure drops developed ACS. The consequences of ACS were prolonged ward-stay at the orthopedic department, a greater need for long-term care after discharge, and poor walking ability at discharge and six months after surgery. The confused patients also had more complications, such as urinary problems, feeding problems and decubital ulcers, as compared with the nonconfused patients.