Two experiments were carried out to evaluate the influence of temperatures on the percentage of germination of Brachiaria brizantha seeds in a laboratory test. It was used the temperatures of 20, 25, 30 and 35°C in the first experiment and 20, 25 and 30°C in the second. According to Levene statistical test, the variance between each treatment was different for the first count in both experiments. The equality was among the results of the percentage of seed germination of the second experiment. The higher the variability was caused by the temperatures. There was no influence of the seed lots or the interaction between temperatures and seed lots.