This research aims to prove empirically the effect of gender diversity and board size on firm performance. Firm performance is measured by using return on assets (ROA). Purposive sampling is utilized in selecting the sample by specific criteria. The number of samples are 24 public-listed companies in Indonesian Stock Exchange for the period of 2015-2019. In total, the number of observations was 120 observations. The samples are collected from S&P. The data for Female proportion, Gender diversity, and Board size were obtained by calculating the number of female directors in the board of directors and calculating the total number of directors in the board of directors while the data which are used for return on assets, were taken from S&P Market Intelligence, accessed regarding to some criteria in the regulation and best practice. Company size, financial leverage, and Firm age will be used as the control variables. The results show that both female proportion and gender diversity does not affect firm performance significantly, while board size has significant effect on firm performance.