—The standard algebraic decoding algorithm of cyclic codes [n, k, d] up to the BCH bound t is very efficient and practical for relatively small n while it becomes unpractical for large n as its computational complexity is O(nt). Aim of this paper is to show how to make this algebraic decoding computationally more efficient: in the case of binary codes, for example, the complexity of the syndrome computation drops from O(nt) to O(t √ n), and that of the error location from O(nt) to at most max{O(t √ n), O(t2 log(t) log(n))}.