This is the proceedings of the SIGAL International Symposium on Algorithms held at CSK Information Education Center, Tokyo, Japan, August 16-18, 1990. SIGAL (Special Interest Group on Algorithms) was organized within the Information Processing Society of Japan in 1988 to encourage research in the field of discrete algorithms, and held 6-8 research meetings each year. This symposium is the first international symposium organized by SIGAL. In response to the call for papers, 88 papers were submitted from around the world. The program committee selected 34 for presentation at the symposium. The symposium also included 5 invited lectures and 10 invited presentations. The subjects of the papers range widely in the field of discrete algorithms in theoretical computer science. Keywords for these subjects are: computational geometry, graph algorithms, complexity theory, parallel algorithms, distributed computing, and computational algebra.