The digital television development is one of the most important events in the history of television broadcasting. This paper highlights the user interface issue in digital television environment. We will not discuss the usability of user interface design, but rather the implementation of user interface for interactive television services. The background of Multimedia Home Platform (MHP) and Application Programming Interface (API) is introduced. The paper describes how to develop a Java user interface, which includes not only graphics but also time-based media (e.g., video). Many functions and effects behind the TV visual image have to be implemented. The special features of digital TV user interface are presented by giving an example (i.e., screen information service for ice hockey). Finally, the future possible research topics are briefly addressed.