The antianginal activity of trimetazidine (Vastarel 20 mg) was evaluated in a double blind study versus placebo. The 54 subjects of the survey were males, of mean age 55.2 +/- 1.4 years in the trimetazidine group and 55.5 +/- 1.8 years in the placebo group, suffering from stable angina. The stability of angina was tested by two exercise tests carried out at the beginning and at the end of a two-week preselection period under placebo. Three tablets daily of either trimetazidine or placebo were given at random for two weeks. At the end of that time, a third exercise test was carried out. The clinical results showed a significant reduction (P less than 0.001) in the number of weekly attacks from 8.1 +/- 0.3 to 2.9 +/- 0.5 under trimetazidine and from 7.6 +/- 0.2 to 4.9 +/- 0.5 under placebo. Moreover, nitroglycerin consumption over a week decreased from 9.1 +/- 0.6 to 3.1 +/- 0.5 tablets under trimetazidine and from 7.9 +/- 0.3 to 5.4 +/- 0.6 tablets under placebo. The difference was significant (P less than 0.001). The global evaluation of the exercise tests showed a significant difference in favor of trimetazidine: 19 patients out of 27 improved under trimetazidine, as compared to 11 out of 27 under placebo. The total workload-capacity after treatment was increased by 62.1% under trimetazidine, and by 24.7% under placebo (P = 0.007). The rate-pressure product diminished by 12% with trimetazidine and by 4% with the placebo. Nevertheless, the interaction was not significant (P = 0.079). This study made it possible to evaluate the significant reduction of stress attacks frequency and nitroglycerin consumption under trimetazidine versus placebo. This clinical improvement was assessed by ergometric parameters.