Purpose: This study aimed to evaluate the effects of exercise training on anxiety symptoms in patients with FM and to examine whether variables of theoretical or practical importance moderate the estimated mean effect. Methods: Twenty-five effects were derived from 10 articles published before June 2016 located using Google Scholar, MEDLINE, PsycINFO, PubMed, and Web of Science. Trials involved 595 patients with FM (mean age = 47.6 yr, 97.5% female) and included both randomization to exercise training (n = 297) or a nonexercise control condition (n = 298) and an anxiety outcome measured at baseline and during and/or after exercise training. Hedges' d effect sizes were computed, data for moderator variables were extracted, and random effects models were used to estimate sampling error and population variance for all analyses. Meta-regression quantified the extent to which patient and trial characteristics moderated the mean effect. Results: Exercise training significantly reduced anxiety symptoms by a mean effect Delta of 0.28 (95% confidence interval [CI] = 0.16-0.40). No significant heterogeneity was observed (Q(24) = 30.79, P = 0.16, I2 = 25.29%). Program duration (A = 1.44, z = 2.50, P <= 0.01) was significantly related to the overall effect, with significantly larger anxiety improvements resulting from programs lasting greater than 26 wk (Delta = 0.35, 95% CI = 0.05-0.66) compared with those lasting less than 26 wk (Delta = 0.26, 95% CI = 0.13-0.39). Conclusion: Exercise training improves anxiety symptoms among FM patients. The findings also suggest that larger anxiety symptom reductions will be achieved by focusing on longer exercise programs while promoting long-term adherence. Future well-designed investigations are required to examine the potential moderating effect of pain-related improvements in FM patients.