The authors report the adaptation of a dietary and risk factor questionnaire and analysis system for use with IBM (or compatible) personal computers. This system includes a flexible computer-assisted interview program which may be modified to suit investigator needs while preserving a standard output format. It also includes a nutrient analysis program for calculation of usual dietary intake. Each of these two major components has its own set of utilities and options, so that investigators may tailor the system to particular research areas. The nature and capabilities of the two main programs are described, as well as the development of the underlying system and the general flow of data in the system.