A prospective study in 16 patient care units in two institutions was conducted to assess patients' risk of falling. Three types of patient care units were utilized (acute medical and surgical, long term geriatric and rehabilitation areas), with 2689 patients over a 4-month period rated daily for fall risk using the Morse Fall Scale. Differences in mean fall score were evident between the acute care areas and the long term and the rehabilitation areas. Examination of the scores in the acute care institution by length of stay, showed different patterns of fall risk; the mean score of the long term patients showed less variation and higher scores. Patients' falls were analyzed by fall score and type of fall. All types of falls (anticipated physiological, unanticipated physiological and accidental), and the severity of injuries increased, with increasing scores indicating clinical validity of the scale.