Background: The well-documented physical benefits of exercise and the value of exercise for improving mental health have raised the profile and role of exercise in healthcare. However, studies evaluating the effects of exercise on neurocognitive function have produced equivocal results. Purpose: This study was designed to examine the effectiveness of exercise on improving cognitive function in older people. Methods: Researchers used a narrative synthesis approach in this review and conducted a computer-based search in MEDLINE, CINAHL, Cochrane Library, and Airiti Library (Chinese) from 2006 to 2009 using the search terms exercise, physical activity, and cognition. Research quality appraisal was rated using Consolidated Standards of Reporting Trials criteria. Result: This review included 12 medium- to high-quality randomized controlled trials. Most studies examined used a 60-minute exercise regimen scheduled three times per week that was continued for 24 weeks. Of the 12 studies, 8 revealed that exercise can improve cognitive function. Five studies focused on healthy older people and three studied older people who had impaired cognition at baseline. Analysis of the studies showed simple, one-component exercise as better for older people with cognitive impairment and multicomponent exercise as better for those without such impairment. Conclusions/implications for practice: This systematic review demonstrated that an exercise regimen of 6 weeks and at least 3 times per week for 60 minutes had a positive effect on cognition. Whether multicomponent exercise is significantly more effective in improving cognitive function, particularly in healthy older people, should be tested using larger trials with more rigorous methodology.