ISAAC 2005, the 16th International Symposium on Algorithms and Computation, took place in Hainan, China, December 19-21, 2005. The symposium provided a forum for researchers working in algorithms and the theory of computation from all over the world. The final count of electronic submissions was 549, of which 112 were accepted. Among them, the submitting authors emails are: 18 from edu (USA) - counts, 14 from de (Germany), 10 from jp (Japan), 8 from fr (France), 8 from hk (Hong Kong), 7 from ca (Canada), 6 from cn (China), 5 from gr (Greece), 4 from gmail, 3 from tw (Taiwan), 3 from it (Italy), 3 from se (Sweden), 3 from sg (Sin- pore), 2 from cz (Czech Republic), 2 from ch (Switzerland), 2 from 163. com, and 1 each from no (Norway), uk (United Kingdom), be (Belgium), au (Australia), es (Spain), nl (The Netherlands), kr (Korea), in (India), il (Israel), cy (Cyprus), cl (Chile), pl (Poland), ie (Ireland), and net. This represents a total of 30 countries or regions, including 3 Internet dot coms. We would like to thank the two invited speaker, Mihalis Yannakakis and Frances Y. Yao, for their insightful speeches and new directions in algorithms and computation. We received 6 nominations for the best paper and 6 nominations for the best s- dent paper. Only papers with all co-authors students could qualify for the latter.