Gender differences in children's emotional experience of math, their math performance, and the relation between these variables were investigated in two studies. In Study 1, test anxiety, math anxiety, and math performance (whole-number computation) were measured in 134 children in grades 3-8 (ages 7-15 years). In Study 2, perceived math competence, math anxiety, and math performance (whole-number computation) were measured in 208 children in grades 3-6 (ages 8-13 years) using data from the study of Jansen et al. ("Learning and Individual Differences," 24, 190-197, 2013). Gender differences occurred only in test anxiety (boys had lower test anxiety than girls). Concerning the relationship between emotional experience of math and math performance, math anxiety and math performance were negatively related, but only for girls, even when controlled for test anxiety (Study 1). However, only the relation between perceived math competence and math performance was significant in Study 2, for both boys and girls. The relation between math anxiety and math performance was not significant in this study after controlling for perceived math competence. Therefore, we might conclude that perceived math competence is a crucial variable when investigating children's emotional experience concerning math.