This study examines the determinants of fund expense ratio in a cross-sectional sample of Malaysian unit trust funds. Since fund performance is a key decisive factor for many investors in selecting mutual funds, and given that fund expenses are an important determinant of fund returns, the information on what factors affect fund expense ratio is becoming more relevant than ever for investors when selecting a fund. The results show that larger funds have lower expense ratios than smaller funds, suggesting the presence of economies of scale. There is also evidence of economies of scope in that funds that belong to a large fund family are found to have low expense ratios. The findings further indicate that funds with high returns volatility are associated with low expense ratios and that high portfolio turnover leads to high expense ratio. There is no evidence that fund objective and fund age are related to fund expense ratio.