Polyphenol supplementation may be useful during exercise. However, there is no evidence indicating yerba mate (YM) increases muscle strength. Thus, this study sought to evaluate the effect of acute YM supplementation on muscle strength following the strength test. In a crossover and pilot clinical trial, ten men were divided into two groups, receiving either supplementation with YM or a placebo. One hour after consumption of beverages, the participants were submitted to tests of one-repetition maximum (1 RM) on the bench press and leg press. The average age of the participants was 25.5 ± 4.1 years, and the average body mass index was 24.4 ± 2.9 kg/m². YM was not able to increase muscle strength when compared to the placebo in either the 1RM leg press exercise (YM: 225 ± 56.2 kg, vs. placebo: 223 ± 64.3 kg, p = 0.743, Cohen’s d = 0.03) or in the 1 RM bench press exercise (YM: 59.5 ± 20.7 kg vs. placebo: 59.5 ± 21.5 kg, p = 1.000, Cohen’s d = 0.) In conclusion, acute intake of YM did not change muscle strength in physically active men.