This book constitutes the refereed proceedings of the International Workshop on Randomization and Approximation Techniques in Computer Science, RANDOM'97, held as a satelite meeting of ICALP'97, in Bologna, Italy, in July 1997.The volume presents 14 thoroughly revised full papers selected from 37 submissions; also included are four invited contributions by leading researchers. The book focuses on algorithms and complexity aspects arising in the development of efficient randomized solutions to computationally difficult problems. The papers are organized in sections on approximation, randomness, algorithms, and complexity.