A multimedia DS-CDMA system using an ARQ reverse link for data transmission is proposed and analysed. The system capacity is evaluated for several error-detecting codes (EDCs) such as the Hamming codes, the Golay code, the extended Golay code and two kinds of BCH codes. A simple new model based on the asymptotic gain for block and convolutional codes is proposed. Using this asymptotic gain model, analytical expressions for the system capacity are derived, which makes the system capacity evaluation easier and faster. The proposed system allows a greater number of data users by using more powerful block EDCs, instead of the Hamming class. The convolutional code efficiency in this system is also discussed.