This study empirically examines the effect of board diversity on the financial performance of listed DMBs in Nigeria. Gender, foreign diversity and ethnic minorities were used as proxies for board diversity and a market based measure, Tobin's Q was used to measure performance. Board size was also used as control variable. Data for the study was extracted from the Nigerian Stock Exchange Fact book and sampled banks' annual reports for the period 2009- 2013. The sample size is thirteen banks chosen based on some selected criteria. The study employed multiple regression technique using Ordinary Least Square in testing the hypotheses of the study. The findings revealed that gender has a positive significant effect on financial performance. Similarly, a positive association was documented between foreigners, and ethnicity on financial performance, although these associations were not significant. However, board size was negative and insignificant. The study recommends that the Security and Exchange Commission (SEC) should ensure that boards of listed DMBs have at least one female director as listing requirement. Also emphasis should be placed on knowledge, skills, and competence when nominating a board member and not race to enhance performance