Objectives: To determine the effect of exercise on the physical function, activities of daily living (ADLs), and quality of life (QOL) of the frail older adults. Data sources: Relevant articles published between 2001 and June 2010 were searched in PubMed, MEDLINE, EMBASE, the Chinese Electronic Periodical Service, CINAHL, and the Cochrane Library databases. Study selection: The participants were selected based on the predetermined frailty criteria and randomly assigned to either an exercise or control group. The intervention for the exercise group was a single or comprehensive exercise training program, whereas usual care was provided to the control group. Data extraction: The characteristics and outcome measures of the included studies were identified independently by 2 investigators. Data synthesis: The effect sizes of physical function assessed by the timed up and go test, gait speed, the Berg Balance Scale (BBS), the ADL questionnaires, and QOL measured by the Medical Outcomes Study 36-Item Short-Form Health Survey were calculated, using a weighted mean difference (WMD) and a 95% confidence interval (CI) to represent the results. Compared with the control group, the exercise group increased their gait speed by .07 m/s (95% CI .02-.11), increased their BBS score (WMD=1.69; 95% CI .56-2.82), and improved their performance in ADLs (WMD=5.33; 95% CI 1.01-9.64). The exercise intervention had no significant effects on the Timed Up & Go test performance and the QOL between the groups. Conclusions: Exercise is beneficial to increase gait speed, improve balance, and improve performance in ADLs in the frail older adults.