A large research project on the subject of computer-aided diagnosis (CAD) entitled "Intelligent Assistance in Diagnosis of Multi-dimensional Medical Images" was initiated in Japan in 2003. The objective of this research project is to develop a multi-organ, multi-disease CAD system that incorporates anatomical knowledge of the human body and diagnostic knowledge of various types of diseases. The present paper provides an overview of the project and clarifies the trend of future CAD technologies in Japan.