In a randomized, double-blind, placebocontrolled study 40 patients with exercise-induced ischemic ST depression were given 75 mg gallopamil in slow release form twice daily. The study had 2 periods. After a 3 day run-in-period and a 14 day open therapy period exercise stress-tests were performed on a bicycle ergometer. 5 patients were dropped from this study. 25 of the remaining 35 patients were "responder" defined as a greater than 30% reduction of the ischemic St depression by gallopamil. These patients were randomly assigned to gallopamil or placebo. At the end of the first open period gallopamil significantly reduced the mean ischemic ST depression by 47% from 0.15 to 0.8 mV (p less than 0.0005). Compared with placebo control, the decrease of the ST depression remained unchanged during gallopamil (0.7 mV). In contrast a statistically significant increase of the ischemic St reaction was observed during placebo. Gallopamil significantly improved exercise tolerance. No side effects or adverse reactions were observed. This study demonstrates that gallopamil slow release is a potent calcium-antagonist in reducing exerciseinduced myocardial ischemia and improving stress tolerance.