Having foreign directors on board has both positive and negative sides while the overall effect of the foreign directors on firm performance is still inconclusive in literature. In this paper, we examine the relation between foreign directors and firm performance measured by return on assets in Vietnam. Using a sample of 175 firms with 955 observations from 2013 to 2019, we find that having foreign directors on board who have better expertise, experience, and networks is positively related to firm performance. However, employing additional foreign directors generally does not bring more benefits due to more misunderstandings and slower decision making, except when all foreign directors are from similar economic development backgrounds. The results contribute to inconclusive literature by adding more understandings of the context in which the foreign directors have an positive impact positively on firm performance. The findings also have practical implications for recruiting foreign directors in Vietnamese firms.