The purpose of the study is to examine if the gender composition of a board has an effect on a company’s financial performance by analyzing their operating margin and return on capital employed (ROCE). The study is based on a quantitative method, studying companies listed on the Stockholm Stock Exchange. Previous research has not been studying the gender composition of boards of Swedish companies and its effect on the company's financial performance in regard to their operating margin and return on capital employed. Therefore, this study has examined that in order to draw a conclusion regarding its possible effects. The data that is collected will be used as support in the analysis in order to understand how the current composition and effects are connected. This study will contribute with knowledge for companies in Sweden regarding gender composition of boards and the possible effects on their financial performance. But also, as support for the ongoing discussion regarding board composition and the current inequality in gender representation. In conclusion the study shows that return on capital employed and the proportion of women in the board has a positive relationship. Meaning that the bigger proportion of women in a board, the better return on capital employed the company has. However, for operating margin there was not a significant relationship and therefore a conclusion regarding that cannot be made.