An inter-symbol interference cancellation method for an orthogonal frequency division multiple access system is provided. The inter-symbol interference cancellation method includes transmitting, at a base station, an OFDMA symbol having a first half part and a second half part divided in time; receiving, at a mobile station, the OFDMA symbol; and restoring the OFDMA symbol by repeating one of the first half part or the second half part. The ISI cancellation method for an OFDMA communication system of the present invention uses an OFDMA symbol having two identical parts sequentially arranged in time, whereby it is possible to recover a transmitted OFDMA symbol if at least one of the two parts is successfully received.