The predictive validity of Katz' Index of ADL (Activities of Daily Living) regarding length of hospital stay, discharge to own home or death within one month, and its reproducibility in clinical practice was studied prospectively in Södertälje and in Enköping, Sweden. The Södertälje study included 124 consecutive patients, who were all assessed on days 5-7 after stroke by an occupational therapist. The Enköping study included 106 consecutive patients, who were assessed similarly by trained nurses. Ninety-six and 94%, respectively, of patients in grades A-C on days 5-7 after stroke were discharged to their own homes within one month. Ninety-six and 92%, respectively, of patients in grades D-G stayed in hospital longer than one month or died. Sixty-two and 68%, respectively, of patients in grade G died within one month. The instrument is now used as a valid tool for early prognosis of stroke outcome in order to facilitate the planning of care and rehabilitation in clinical practice.