The Fourth International Conference on Bio-Inspired Computing: Theories and Applications (BIC-TA 2009) will be held in Peking University, Beijing, following the successes of previous events. BIC-TA 2009 aims to provide a high-level international forum for researchers with different backgrounds working in the main areas of natural computing inspired by biology to present their latest results and exchange ideas. Authors are invited to submit papers presenting original and unpublished research in any aspect of bio-inspired computing.