This article examines the performance of index equity funds in Australia. Despite the significant growth in index funds since 1976, when the first index mutual fund was launched in the U.S., research on their performance is sparse in the U.S. and non-existent in Australia. This study documents the existence of significant tracking error for Australian index funds. For example, the magnitude of the difference between index fund returns and index returns averages between 7.4 and 22.3 basis points per month across index funds operating for more than five years. However, there is little evidence of bias in tracking error implying that these funds neither systematically outperform nor underperform their benchmark on a before cost basis. Further analysis provides evidence that the magnitude of tracking error is related to fund cash flows, market volatility, transaction costs and index replication strategies used by the manager.