Retail investors face a dilemma in selecting funds from among the wide range of schemes available. The past performance of a fund is not always indicative of its future performance, but it is the only quantitative way to judge how good a fund is at present. Investors always prefer funds which give high returns and have low risk. Thus while building a fund portfolio the fund manager should understand the impact of portfolio allocation in different instruments on the performance of the portfolio. The objective of the present study was to find the short-term effects of portfolio allocation on the performance of mutual funds. The data for the study consisted of the portfolio allocations and the performance measures of a sample of one hundred and nineteen open-ended mutual fund schemes, of which thirty-eight were diversified debt/ income funds, forty-eight were diversified equity funds, twenty-one were balanced funds, and twelve were short-term debt funds. The performance measures used for the analysis were: mean returns, standard deviation in returns, beta, and Sharpe ratio. The portfolio allocation of the funds was described both in terms of the percentage allocated in equity, debt, and cash & equivalents, and in terms of the percentage allocated in different sectors. The data was entirely secondary data, and was collected from the AMFI website. The findings of the study indicate that, for different types of funds, allocation in different asset classes, that is, equity, debt, and cash & equivalents, as well as their sector-wise allocation tend to impact the performance of the fund.