This paper examines the relationship between boards of directors' demographic diversity and firms' financial performance. In particular, we highlight how women and ethnic minorities can affect Middle Eastern SMEs' financial performance. Using an unbalanced panel of 1,855 firm-year observations of 371 boards of directors from nine Middle Eastern countries, our results support the positive impact of women and ethnic minority group members on Middle Eastern firms' performance. However, our evidence implies that when Western ethnic minority members increase, firms' performances tend to decrease, because these board members are appointed for regional and international board reputation legitimacy, personal business agendas, and links to the external corporate environment.