Abstract : It is shown that the Lyndon decomposition of a word of n symbols can be computed by an n-processors CRCW PRAM in O(log n) time. Extensions of the basic algorithm convey, within the same time and processors bounds, efficient parallel solutions to problems such as finding the lexicographically minimum or maximum suffix for all prefixes of the input string, and finding the lexicographically least rotation of all prefixes of the input.