EXPE is a DOS program for the design and running of experiments that involve the presentation of audio or visual stimuli and the collection of on-line or off-line behavioral responses. Its flexibility makes it also a very useful tool for the rapid design of protocols for testing neu-ropsychological patients. EXPE provides a powerful scripting language which allows the user to specify all the components of an experiment in a human readable file. Subjects' responses are saved in a user-specified format, also in readable ASCII files. A remarkable feature of EXPE is that the user can easily add new commands to the language: all the instructions are calls to functions written in independent Borland Pascal units. Thus, users can link their own pascal procedures to EXPE to meet any special need. This makes it possible, for example, to adapt EXPE to new hardware, such as new sound or video boards.