This paper investigates the effects of certain corporate governance mechanisms on the performance of firms listed on the Nigerian Stock Exchange. Based on a sample of 93 firms for the period 1996 through 1999, our results show an optimal board size of ten, favour concentrated over diffused ownership, and support separation of posts of CEO and chair. Moreover, while director shareholding is found to be an insignificant factor affecting firm performance, the results show expatriate CEOs performing better than their local counterparts. We need to err on the side of caution as sampling selection was based on data availability rather than any probability criterion.