||In current world we can observe a substantial gender gap in the labor market as women tend to earn considerably less than men. One of the possible explanations of the wage gap might be the gap in the competitivness. Recent experimental economic literature has shown that there are differences between men and women in the preference to compete. In this study I explore competitiveness among children from the Czech Republic. Using a field experiment with a real task, I found that both boys and girls react to the competitive environment, but boys do compete significantly more than girls indicating a presence of the gender gap. On the contrary, age, number of siblings and activities, and education of parents do not affect the performance under competitive scheme.