The time point generally recognized as most appropriate to assess final functional outcome after acute ischemic stroke is 3 months. However, identifying earlier reliable prognostic time points may allay patient anxiety about the recovery process, enable assignment of outcome in patients lost to follow-up, and provide earlier and more readily available options for clinical outcome assessment in adaptive design and proof of concept studies. We assessed whether day-7/10 functional outcome predicted day-90 functional outcome among acute ischemic stroke patients. The NINDS-tPA Study database was analyzed. Global disability was assessed using the modified Rankin Scale (mRS). Spearman correlation evaluated the association of day-7/10 versus day-90 mRS, and observed agreement was computed using the weighted kappa agreement, both unadjusted and adjusted by multivariable ordinal logistic modeling for demographic and clinical variables known to influence stroke outcomes. 581 subjects (93%) were alive at 7-10 days. There was strong correlation between mRS score at day 7/10 and day 90 (r = 0.81, p < 0.0001), and the weighted kappa agreement was 0.82 (p < 0.0001). In multivariable analysis, day-7/10 day mRS was independently and strongly associated with day-90 mRS, while among other baseline variables, only baseline NIH Stroke Scale score (per unit increase) and a history of congestive heart failure (CHF) were significantly associated with a worse day-90 mRS. Global disability status 1 week after an index ischemic stroke strongly predicts final 3-month disability outcome. Functioning at 1 week, supplemented by initial stroke severity and CHF history information, may provide an early outcome guide useful for patient and family counseling.