Mathematics is one of the most difficult and important school disciplines and causes subjective difficulties for many students. Many factors and predictors affect of the mathematical performance and achievements of children. This article examines gender stereotypes in mathematics as a predictor of motivational achievements. Most studies found that boys perceive mathematics to be more “masculine” than girls. To determine whether such a stereotype exists among Bulgarian students, a study was done. It was established that boys considered that mathematics is a masculine discipline. In high school students, this trend is more pronounced that for to students or schoolchildren from the 5th to the 9th grade.