Intelligent Data Engineering and Automated Learning (IDEAL) was initially a biennial forum dedicated to emerging and challenging topics in intelligent data analysis, knowledge discovery, and statistical and computational learning. The huge success of recent IDEAL conferences and the continuous growth of the ?eld have compelled it to become an annual conference after 2003. It is now a major international, interdisciplinary event covering subjects from data mining, inf- mation retrieval and management, autonomous learning, and agents to ?nancial engineering, neural networks, emerging learning paradigms and systems, bio- formatics, and pattern recognition. Data analysis and processing has become a common theme and plays a crucial role in many disciplines, especially in ?nance, biology, engineering, and information technology. Demand for intelligent met- dologies and tools is immense. The multidisciplinary nature of current research is pushing the traditional boundaries and bringing new ideas and solutions, and it is the way forward. This volume contains 164 refereed and ?nally accepted papers presented at the4thInternationalConferenceonIntelligentDataEngineeringandAutomated Learning (IDEAL 2003), held in Hong Kong, March 21-23, 2003. IDEAL 2003 received a record level of submissions, 321 in total, from all over the world. They were subsequently peer-reviewed by the Program Committee. The conference was held together with the 2003 IEEE International Conference on Computat- nal Intelligence for Financial Engineering at the modern and magni?cent Hong KongConventionandExhibitionCentre.