Ventricular tachyarrhythmias commonly occur in trained athletes during ambulatory Holter electrocardiography and are usually associated with a benign course. Such arrhythmias have been demonstrated to be sensitive to short periods of athletic deconditioning; however, their response to retraining is not known. Twenty-four hour Holter electrocardiographic monitoring was performed at peak training and after 3 to 6 months of deconditioning and was repeated in the present study after 2, 6, and 12 months of retraining in 37 athletes with frequent and complex ventricular tachyarrhythmias and without cardiovascular abnormalities. These subjects showed partial (101 to 500 ventricular premature complexes [VPCs]/24 hours) or marked (<100 VPCs) reversibility of arrhythmias after deconditioning. Retraining initially resulted in a significant increase in arrhythmia frequency compared with deconditioning (from 280 ± 475 to 1,542 ± 2,186 VPCs; p = 0.005), couplets (0.14 ± 0.42 to 4.4 ± 8.2; p = 0.005), and nonsustained ventricular tachycardia (from 0 to 0.8 ± 1.8; p = 0.02). Subsequently, a progressive reduction was seen in the frequency of all ventricular arrhythmias during the 1 year of training to well below that at the peak training levels (VPCs 917 ± 1,630, couplets 1.8 ± 4.2, and nonsustained ventricular tachycardia 0.4 ± 1.2). Such annual arrhythmia reduction was significantly greater statistically in those athletes with marked reversibility after deconditioning than in the athletes with partial reversibility (69 ± 139 vs 1,496 ± 1,917 VPCs/24 hours, respectively; p = 0.007). No cardiac events or symptoms occurred during 1 year of follow-up. In conclusion, in elite athletes without cardiovascular disease, a resumption in intense training after deconditioning was associated with variable, but prolonged, suppression of ventricular ectopy. The absence of adverse clinical events or symptoms associated with the resumption of training supports the continued eligibility in competitive sports for such athletes and is also consistent with the benign nature of physiologic athlete's heart syndrome.