This book constitutes the thoroughly refereed papers of the 17th International Conference on Implementation and Application of Automata, CIAA 2012, held in Porto, Portugal, in July 2012. The 21 revised full papers presented together with 5 invited papers and 7 short papers were carefully selected from 53 submissions. The papers cover various topics such as automata applications in formal verification methods, natural language processing, pattern matching, data storage and retrieval, and bioinformatics, as well as theoretical work on automata theory.