Gait and balance disturbances have been shown to predispose to falls in hospital. We aimed to investigate the patient characteristics associated with an unsafe gait and to determine what features predispose to falling in this group of hospital inpatients. In a prospective open observational study we studied 825 patients admitted for rehabilitation following acute medical illness or a surgical procedure. The patient's gait was assessed with the 'get up and go' test and classified into one of four categories-normal; abnormal but safe with or without mobility aids; unsafe; or unable. 72.6% of patients were assessed as having an unsafe gait. The factors independently associated with an unsafe gait were confusion, abnormal lower limbs, hearing defects and the use of tranquillizers. Patients with an unsafe gait who fell were more likely than the non-fallers within the group to have had falls in the past (85.3% versus 73.8%) and to be confused (66.2% versus 34.1%). Patients with both these characteristics had a 37.5% chance of falling compared with 15.4% in patients with one and 11.2% in patients with none of these characteristics. The presence of confusion and a history of falls identifies those patients who are at greatest risk of falls. Such patients might be the focus of special efforts at falls prevention.