BACKGROUND Predisposing factors alone explain only a limited proportion of the variation in fall events, especially in people with dementia. The aim of this study was to identify precipitating factors for falls among people with dementia. METHODS We examined prospective fall registrations over a two-year period on a psychogeriatric hospital ward in the north of Sweden. Circumstances associated with each fall event were analyzed by independent reviewers, possible precipitating factors were documented, evaluated and the most likely precipitating factors were identified. In total, 223 patients with any type of diagnosed dementia were admitted to the ward and 91 fell at least once. Of these, 46 were women and 45 were men (mean age 80.3 years, range 60-94). RESULTS A total of 298 falls were registered, 62% of which were sustained by men. The most likely factor or combination of factors could be ascertained in 247 falls (83%). Falls took place at all hours but almost half of the falls (44%) occurred during the nightshift (between 9 pm and 7 am). Acute disease or symptoms of disease and/or acute drug side-effects were, alone or in combination with other factors, judged to precipitate more than three out of four falls. CONCLUSIONS It is possible to identify many precipitating factors that may contribute to a fall. Falls in people with dementia should be regarded as a symptom of acute disease or as a drug side-effect until proven otherwise. Prompt detection of these relevant factors is, therefore, essential.