Disclosure is a prerequisite to receive disease-specific social support. However, in the case of a stigmatised disease, it can also lead to discrimination. We aimed to assess disclosure rates of HIV patients and the reactions they encountered in comparison to patients with chronic viral hepatitis or diabetes mellitus and patients' general perception of disease-specific discrimination. We constructed a self-report questionnaire, anonymously assessing the size of the social environment, the persons who had been informed, and the experienced reactions as perceived by the disclosing patients, to be rated on 1-4 point Likert scales. In addition, patients were asked whether they perceive general discrimination in Germany. One hundred and seventy-one patients were asked to participate. Five rejected, thus questionnaires from 83 patients with HIV, 42 patients with chronic viral hepatitis B (n = 9) or C (n = 33), and 41 patients with insulin-dependent diabetes mellitus (type I n = 14, type II n = 27) were analysed. Whereas the size of the social environment did not differ, HIV-infected patients were least likely to disclose their disease (60.7%, SD ± 31.9) to their social environment as compared to patients with chronic viral hepatitis (84.2 ± 23.3%, p<0.0001), or diabetes mellitus (94.4 ± 10.3%, p<0.0001), respectively. Within the HIV patient group, the mean disclosure rate was highest to partners (90.9%), followed by the public environment (65.2%), friends (59.4%) and family members (43.8%). HIV patients experienced supportive reactions after 79.3 ± 26.4% of disclosures, which was the case in 91.4 ± 19.6% and 75.7 ± 36.1% of patients with hepatitis or diabetes mellitus, respectively. 69.5% of HIV patients stated to perceive general discrimination in Germany. We conclude that HIV patients had experienced supportive reactions after the majority of disclosures, but the low rate points out that their information strategy had been very selective. Societal discrimination of HIV patients is still an issue and needs to be further addressed.