Macaulay Duration is the time taken for the price of a bond to repay to investors through cash-flows including both interest payments and principal repayments. Macaulay Duration of a debt fund portfolio is calculated weighted average time period over which the cash-flows from the underlying bonds in the portfolio is received. Price of bond has an inverse relationship with interest rate changes. If interest rate goes up, bond prices fall and vice versa. A bond with longer Macaulay Duration is more sensitive to interest rate changes. Hence it is important for investors to know the Macaulay Duration of the scheme they are investing in.