Some mental health experts have suggested that particular subgroups of the chronic mentally ill may be especially vulnerable to human immunodeficiency virus (HIV) infection. Patients with mood disorders (manic type), schizophrenia, and dual diagnosis of either disorder with substance abuse are considered at high risk for HIV infection, as are psychiatric patients with poor judgment, hypersexuality, and impulsivity, characteristics that interfere with practicing safer sexual and/or drug-related behaviors. A major problem is how to adapt HIV prevention programs to take into account these clinical characteristics. Given the types of cognitive deficits that many psychiatric patients have, it may be useful to adapt HIV prevention efforts for this population by: (1) not providing too much information at one time; (2) being explicit; (3) keeping explanations simple; (4) using concrete examples of future interpersonal situations the patient is likely to encounter; (5) using repetition; (6) applying the guidelines of being concrete, simple, and repetitive by developing group exercises that apply to the principles of safer sex; (7) using humor; and (8) developing a supportive alliance with the patients before providing HIV information or attempting behavioral change. A psychoeducational model may be useful. Before any type of prevention program can be implemented, mental health professionals must not only master basic HIV information, but must become comfortable talking about sex with their patients. (NB)