This paper describes a fixed-point implementation method of the unified speech and audio coding (USAC) decoder that has been recently standardized by moving picture experts group (MPEG). Since the structure of USAC is too complicated to support both speech and audio signals, the quality and complexity issues must be carefully reviewed while performing fixed-point implementation. By analyzing the structure of the USAC decoder, this paper describes key ideas to successfully realize the fixedpoint system. Subjective and objective test results verify that the implemented fixed-point decoder shows equivalent quality to the floating-point decoder. The average and worst cases of complexity depending on the type of encoding modes are also given in detail.