Hypertext is a new computer-based method of presenting information that provides greater flexibility than conventional methods of continuing education. With a hypertext system, an individual using the computer can acquire more information on a word or concept that needs to be pursued in depth. Hypermedia is an expanded concept which uses the computer's ability to incorporate images, sounds, and video images in addition to text. This interactive, multimedia approach customizes information for more effective learning. The authors devised a prototype hypermedia textbook of nuclear medicine using a personal computer with hypermedia software that contains text, graphs, tables, figures, literature citations, and an easily persuable image database. All the information is organized with multiple cross-references, allowing instant branching to relevant facts, in different levels of detail. The system's applications and the ease of expansion or modification by the user are described.