This book constitutes the refereed proceedings of the Second International Workshop on Randomization and Approximation Techniques in Computer Science, RANDOM'98, held in Barcelona, Spain, in October 1998. The 26 revised full papers presented were carefully reviewed and selected for inclusion in the proceedings. Also included are three invited contributions. Among the topics addressed are graph computation, derandomization, pattern matching, computational geometry, approximation algorithms, search algorithms, sorting, and networking algorithms.