We consider a concatenated coded system consists of an inner error correcting code and an outer error detecting code. In a conventional decoding scheme, the inner decoder produces the best codeword from its perspective. The best codeword is then checked by the outer decoder. The performance of the concatenated coded system can be improved by having the inner decoder produce not only the most likely candidate but also other highly likely candidates. In this paper, we propose a new algorithm called ?perturbed decoding algorithm? (PA). In PA, other highly likely candidate is produced by feeding the inner decoder with slightly perturbed versions of the received signal. The concept of PA is compatible with most combinations of inner code and outer code. Because PA does not require the use of a sophisticated inner decoder, it is straightforward to implement in silicon technology. From our simulation, PA can achieve a performance gain greater than 1 dB.