In the past decade, several studies have reported potential prognostic factors for aphasia after stroke. However, these reports covered no more than 1 year after stroke onset, even though patients often continue to improve over longer periods. The present study included 121 patients with aphasia who received cognitive-based linguistic rehabilitation for at least 2 years post-onset. All were right-handed and had a lesion only in the left hemisphere. Aphasia outcome was predicted using multiple linear regression analysis. Age at onset, lesion in the left superior temporal gyrus including Wernicke's area, and baseline linguistic abilities including aphasia severity and both phonological and semantic functions were significant predictors of long-term aphasia outcome. These findings suggest that the long-term outcome of aphasia following adequate linguistic rehabilitation can be predicted by age at onset, lesion area, and baseline linguistic abilities and that linguistic rehabilitation is particularly recommended for younger individuals with aphasia.