In this paper, we introduce our experience on the development of a three-dimensional audio-visual(3D AV) service system based on the terrestrial digital multimedia broadcasting (T-DMB) system. 3D AV service is now much more feasible than before with the fast advancement of hardware technologies, especially 3D flat panel display, processors and memory. 3D AV service over DMB system is very attractive due to the facts that (1) glassless 3D viewing with small display is relatively easy to implement and more suitable to the single user environment like DMB, (2) DMB is a new media and thus has more flexibility in adding new services on the existing ones, (3) 3D AV handling capability of 3D DMB terminal has lots of potential to generate new types of services if it is added with other components like built-in stereo camera. In order to provide successful 3D DMB services over existing DMB system, we need to solve several issues like (1) guaranteeing backward compatibility with the T-DMB system, (2) minimizing the overhead on the transmitted bit-rate and the required processing power of the terminal, (3) providing good 3D depth perception without a noticeable eye strain. We propose a very efficient and backward compatible system architecture for the 3D DMB, and show how we can get better depth perception with the limited bit budget of the DMB system.