Abstract Background: This study is the result of the anecdotal observation that a number of patients with atrial fibrillation (AF) had noted reversion to sinus rhythm (SR) with exercise. We aimed to evaluate the potential role of exercise stress test (EST) for the reversion of AF. Methods: Patients with AF who were scheduled to undergo electrical cardioversion (DCR) underwent EST using a modified Bruce protocol. Results: Eighteen patients (16 male); aged 36–74 years (mean 58 years) were studied. Five patients (27.7%) had successful reversion with exercise (group 1). Thirteen patients remained in AF (group 2). No patient who failed to revert with exercise did so spontaneously before DCR 3 h to 7 months later (median 20 days). Comparison between group 1 and group 2 did not reveal any significant difference Conclusion: This small preliminary study suggests that in some patients it may be possible to revert AF to SR with exercise and avoid DCR and concomitant general anaesthesia. The authors suggest that a larger multicentre randomized trial is warranted to confirm or refute these initial results and if correct identify those who might benefit.