In previous studies done at our center it has been demonstrated that AIDS is associated with remarkably high rates of neurological complications and organic mental disorders. The prevalence of organic mental disorders in patients with AIDS is estimated to be 65%, with delirium and dementia being the two most common types. At this time there is no published systematic research to guide clinicians in the effective and safe pharmacologic management of delirium in the AIDS population. The drug of choice in treating delirium in the medically ill is haloperidol, a high potency neuroleptic. Recent reports and our own clinical experience suggests that patients with AIDS and neurological complications may have an unacceptably high level of sensitivity to the extrapyramidal side effects of high potency neuroleptics like haloperidol. These findings led us to propose this study to test the efficacy and safety of three drug treatment interventions; 1) high potency (haloperidol) vs. low potency neuroleptic (chlorpromazine) vs. benzodiazepine (lorazepam) in medically hospitalized AIDS patients with delirium. This controlled medication trial will examine the differential therapeutic effects and side effects of these drug treatments for delirium and will identify predictors of response, non-response and treatment limiting side effects that may exist in the AIDS population. AIDS patients with delirium will be studied in a double-blind stratified random assignment repeated measures design. Outcome measures of delirium, cognitive function, psychiatric status, medical and neurological status, extrapyramidal symptoms and side effects will be repeatedly assessed by an evaluating clinician. The treating clinician will follow a standardized treatment protocol. Data from this study will be useful not only in the treatment of HIV-related organic mental disorders, but also in the treatment of delirium in the medically ill. This has been little studied, but is becoming a larger health care problem as the AIDS epidemic grows.