The current study has been commenced to interrogate the link between fund size and equity mutual fund performance in Pakistan, which was rarely discussed in Pakistan. Although, numerous different studies depict the performance of equity mutual funds in Pakistan, which helps the investor in making better investment decisions, but still this area of research is somewhat untapped and a room for the improvement still available. The study focuses to find out the relationship between fund size and mutual fund by taking 12 equity mutual funds of Pakistan as a sample size and further characterized them according to their holding assets (Small size, Medium size and Large size) and collected the net asset value of the last trading/transaction day of each quarter for the tenure of 5 years (2010-2014). The techniques used for the evaluation is regression and correlation. The results of the study demonstrate by using the statistics of 12 equity mutual fund company's average net asset value and standard deviation for 5 years (2010-2014) and the utilization of limited duration and limited variables as a performance measure predicts the limitation of the basic study and reported that the fund sizes (small size, medium size and large size) directly and positively impact over the performance of equity mutual funds in Pakistan.