Extensive research has evaluated mutual fund performance in different financial markets which led to mixed results (Soderlind et al., 2000; Korkeamaki and Smythe, 2004), however, limited work has been done to evaluate Pakistani mutual funds. The purpose of this study is to provide guidelines to the managers of open-ended Pakistani mutual funds and benefit small investors by pointing out the significant variables influencing the fund performance. An effort has been made to measure the fund performance by using Sharpe ratio with the help of pooled time-series and cross-sectional data and focusing on different fund attributes such as fund size, expenses, age, turnover, loads and liquidity. The quarterly sample data are collected for all the open-ended mutual funds listed on Mutual Fund Association of Pakistan (MUFAP), for the years 1999-2006. The results indicate that among various funds attributes lagged return, liquidity and 12B-1 had significant impact on fund performance.