The purpose of the present study was to determine whether mental health professionals would breach the confidentiality of HIV-infected patients with uninformed sex partners, and how any such disclosure would occur. Subjects read one of eight vignettes that depicted a patient who refused to disclose his viral status. Results revealed a split of opinion about breaching confidentiality and about the preferred mode for doing so. Neither diagnosis nor mode of viral transmission significantly influenced breaching decisions. Subjects demonstrated a high level of AIDS risk knowledge but only a moderate level of legal/ethical knowledge. Implications of these findings are discussed.