This book constitutes the refereed proceedings of the 5th Pacific Rim International Conference on Artificial Intelligence, PRICAI'98, held in Singapore, in November 1998.The 56 revised papers presented were carefully reviewed and selected from a total of 197 submissions received from 25 countries. The papers are organized in sections on induction; multi-agent architecture; knowledge acquisition, modeling and validation; reasoning; knowledge discovery and data mining; knowledge management; application of fuzzy logic; applications of neural networks; searching; Bayesian networks; text analysis; knowledge structure; inductive logic programming; intelligent systems; foundations of AI; stochastic processes; abduction; information retrieval and speech recognition.