The Third International Workshop on Hybrid Artificial Intelligence Systems (HAIS 2008) presented the most recent developments in the dynamically expanding realm of symbolic and sub-symbolic techniques aimed at the construction of highly robust and reliable problem-solving techniques. Hybrid intelligent systems have become incre- ingly popular given their capabilities to handle a broad spectrum of real-world c- plex problems which come with inherent imprecision, uncertainty and vagueness, high-dimensionality, and non stationarity. These systems provide us with the oppor- nity to exploit existing domain knowledge as well as raw data to come up with prom- ing solutions in an effective manner. Being truly multidisciplinary, the series of HAIS workshops offers a unique research forum to present and discuss the latest theoretical advances and real-world applications in this exciting research field. This volume of Lecture Notes on Artificial Intelligence (LNAI) includes accepted papers presented at HAIS 2008 held in University of Burgos, Burgos, Spain, Sept- ber 2008 The global purpose of HAIS conferences has been to form a broad and interdis- plinary forum for hybrid artificial intelligence systems and associated learning pa- digms, which are playing increasingly important roles in a large number of application areas. Since its first edition in Brazil in 2006, HAIS has become an important forum for researchers working on fundamental and theoretical aspects of hybrid artificial intel- gence systems based on the use of agents and multiagent systems, bioinformatics and bio-inspired models, fuzzy systems, artificial vision, artificial neural networks, opti- zation models and alike.