This book constitutes the refereed proceedings of the 26th InternationalSymposium on Algorithms and Computation, ISAAC 2015, held in Nagoya, Japan, inDecember 2015.

The 65 revised full papers presented together with 3 invited talks were carefullyreviewed and selected from 180 submissions for inclusion in the book. The focusof the volume is on the following topics: computational geometry; datastructures; combinatorial optimization and approximation algorithms; randomizedalgorithms; graph algorithms and FPT; computational complexity; graph drawingand planar graphs; online and streaming algorithms; and string and DNAalgorithms.