This book contains selected papers presented at the International Conference "Bio-Inspired Computational Methods Used for Difficult Problems Solving. Development of Intelligent and Complex Systems" - BICS 2008, organized by the Romanian Academy, Bucharest and Petru Major University of Tg. Mures, held on 5-7 November 2008 at Petry Major University of Tg. Mures, Romania. The aim of this conference was to bring together researchers working in the main areas of Complex Systems, Artificial Intelligence, Intelligent Systems and Natural Computing for presenting their recent results and exchanging ideas. The papers included in the book provide an introduction and also a state of the art to the bio-inspired computer science. The areas covered were those of natural computing, such as evolutionary and neural computing, as well as younger research directions, such as DNA computing, ant colony optimization, with connections and applications to intelligent complex systems and to medical informatics. Thus, both directions of research, from biology to informatics and from informatics to biology are illustrated.