Reviewed 273 medical records and interviewed 42 referring physicians to examine effectiveness of geriatric day hospital (GDH). Found that GDH provided intensive outpatient care, geriatric assessment, rehabilitation, and alternative to hospitalization: 21 percent of physician-referred patients would have been hospitalized without GDH, 7 percent would have had longer hospital stays, and care would have been deferred for 18 percent. (Author/NB)