Time course and degree of recovery of upper extremity (UE) function after stroke and the influence of initial UE paresis were studied prospectively in a community-based population of 421 consecutive stroke patients admitted acutely during a 1-year period. UE function was assessed weekly, using the Barthel Index subscores for feeding and grooming. UE paresis was assessed by the Scandinavian Stroke Scale subscores for hand and arm. The best possible UE function was achieved by 80% of the patients within 3 weeks after stroke onset and by 95% within 9 weeks; in patients with mild UE paresis, function was achieved within 3 and 6 weeks, respectively, and in patients with severe UE paresis within 6 and 11 weeks, respectively. Full UE function was achieved by 79% of patients with mild UE paresis and only by 18% of patients with severe UE paresis. A valid prognosis of UE function can be made within 3 and 6 weeks in patients with mild and severe UE paresis, respectively. Further recovery of UE function should not be expected after 6 and 11 weeks respectively, in these groups of patients.