One limiting issue in implementing high-speed wireless systems is the impairment associated with analog processing due to component imperfections. In uplink transmission of multiuser systems, a major source of such impairment is IQ imbalance (IQI) introduced at multiple transmitters. In this paper, we analyze the effect of the transmitter (Tx) IQI on OFDMA receiver. To cope with the inter-user interference problem due to Tx IQI, we propose a novel subcarrier allocation scheme, which has high tolerance to such Tx IQ distortion.