The MUTAN (Tanzanian Norwegian AIDS Project) virology program has comprised research, intervention, surveillance, and education as part of the Tanzanian National AIDS Control Program. The introduction of a HIV/AIDS counseling service at the regional hospitals of Arusha and Kilimanjaro during 1990-92 is described. Patients were given pre-test, post-test, and follow-up counseling by 15 trained counselors from the hospitals. In addition, all doctors underwent a 2-day training course in counseling. A total of 1194 patients were included in the pretest counseling of whom 1133 (95%) gave informed consent to be tested. 930 persons (78%) were directed to doctors in the hospitals. 15% of the 1194 turned to counselors on their own initiative. Of 1108 persons who had test results, 684 (61.7%) were HIV positive. Out of 1133 patients who gave informed consent, 765 (360 men and 405 women) were evaluated. No symptoms were found in 17.3% of men and 35.7% of women; earlier signs of AIDS were verified in 59.3% of men and 67.7% of women; clinical symptoms of AIDS were revealed by 90.4% of men and 85.5% of women; and terminal AIDS was diagnosed in 65.5% of men and 83.3% of women. The data showed that the clinical diagnosis of mistaken early AIDS was very uncertain; however, there was a high degree of correspondence between the clinical diagnosis of manifest AIDS and the serological results. In increasing order the psychosocial reactions to the positive test results were: shock, denial, anger, relief (p .05), guilt feeling (p .05), fright/anxiety, dejection/sorrow, and acceptance. This mode of counseling became routine after 5 years in the two hospitals. About two-thirds of the HIV positive patients from the 1990-92 period died, but the counseling system allows the follow-up of HIV-positive patients and their families in devising methods for fighting the epidemic.