Objective In this study, we aimed for the first time to evaluate the effectiveness of atomoxetine (Strattera) in the treatment of cognitive impairment and aphasia after stroke in a large sample. Methods We reviewed the data of 106 patients with poststroke aphasia and cognitive impairment (atomoxetine treatment group = 55 patients vs control group = 51 patients), including scores of the Korean version of the Mini-Mental State Examination (K-MMSE) and the Korean version of the Western Aphasia Battery. Wilcoxon signed-rank tests were used to compare the initial and follow-up K-MMSE and Korean version of the Western Aphasia Battery scores. Mann-Whitney U tests were used to compare the degree of improvement in K-MMSE and Aphasia Quotient (AQ) scores between the atomoxetine and control groups. Results Baseline characteristics including age, years of education, and scores of the initial Functional Independence Measure, Korean version of the Modified Barthel Index, Hamilton Depression Rating Scale, K-MMSE, and AQ did not differ significantly between the 2 groups. Follow-up K-MMSE and AQ scores were significantly better than the initial scores in both the treatment and control groups. However, improvements in K-MMSE scores were significantly greater in the treatment group than in the control group. In addition, the atomoxetine group had significantly higher AQ scores than the control group, especially for auditory verbal comprehension and naming. Conclusions Atomoxetine has been shown to significantly improve cognitive function and language in patients with poststroke aphasia. It is also the first study to report improvement in auditory comprehension and naming by administration of atomoxetine.