OBJECTIVES: To determine the clinical predictors and prognostic significance of exercise-induced non-sustained ventricular tachycardia (NSVT) in a large population of asymptomatic volunteers. Background: Prior studies report variable risk associated with exercise-induced ventricular arrhythmia. METHODS: Subjects in the Baltimore Longitudinal Study of Aging free of known cardiovascular (CV) disease who completed at least one symptom-limited exercise treadmill test between 1977 and 2001 were included. NSVT episodes were characterized by QRS morphology, duration, and rate. Subjects underwent follow-up clinical evaluation every two years. RESULTS: The 2099 subjects (mean age 52.0 yrs, 52.2% male) underwent a mean of 2.7 exercise tests, on which 79 (3.7%) developed NSVT with exercise on at least 1 test. The NSVT had median duration of 3 beats (≤5 beats in 84%), and median rate of 175 bpm. Subjects with (vs. without) NSVT were older (67±12 yr vs. 51±17 yr, p < 0.0001), and more likely to be male (80% vs 51%, p< 0.0001), and to have baseline ECG abnormalities (50% vs. 17%, p<0.0001) or ischemic ST segment changes with exercise (20% vs 10%, p=0.004). Over a mean follow-up of 13.5 ± 7.7 yrs, 518 deaths (24.6%) occurred. After multivariable adjustment for age, sex, and coronary risk factors, exercise-induced NSVT was not significantly associated with total mortality (HR=1.30 [95% CI 0.89-1.90], p=0.17). CONCLUSIONS: Exercise-induced NSVT occurred in nearly 4% of this asymptomatic adult cohort. This finding increased with age and was more common in men. After adjustment for clinical variables, exercise-induced NSVT did not independently increase risk of total mortality.