From January 1989 to December 1990, 7653 phone calls were answered by the AIDS Hot Line of the Centre Hospitalier Universitaire Vaudois. Most of the calls were from the general public (82%), 12% from health care workers and 6% from HIV-infected subjects. The main reasons for calling were information regarding the HIV test (public), scientific inquiries (health care works) and requests for medical or social support (HIV-positive persons). With more than 15 phone calls per day, this hot line fulfils a definite need with respect to the various types of information required.