OBJECTIVE To establish how many hospitalisations of nursing home patients are realised annually, the characteristics of these patients and the diagnoses and the purposes for which they are hospitalised. METHODS Retrospective and prospective. METHODS Analysis of national data for the 5-year period 1986-1990 obtained from the registration of nursing home patients (SIVIS) of the Dutch Centre of Health Care information (SIG) and analysis of 385 separately gathered registration data from 30 nursing homes. RESULTS More than 9000 hospitalisations of nursing home patients were realised annually, over 10% of those who stay in a nursing home for a shorter or longer time. Somatic patients were hospitalised nearly twice as often as psychogeriatric patients, and men about 1.25 times more often than women. The probability of hospitalisation decreased with advancing age. The most frequent reasons for hospitalisation were cardiovascular diseases, digestive tract diseases and femoral neck fractures. The most important purposes of hospitalisation are: to ward off threat to life (31%), to remedy complaints and burdens (29%), to improve the general condition (16%) and diagnostics (16%). The probability of hospitalisation was 2.5 times as large for the elderly living at home as for older nursing home patients. CONCLUSIONS Hospitalisations are an important part of medical treatment and care of nursing home patients. There is a variation in hospitalisation rates for different categories of patients. Objectives of hospitalisation are diverse. There is a need for research into the effects of hospitalisation on the quality of life.