The courts have consistently ruled that State officials have the power to impose a quarantine when public health concerns make this necessary. However, nearly all public health officials pose this measure with respect to AIDS, which is not spread by casual contact. The most extensive quarantine would be the forced isolation of all persons infected with HIV. Such an approach would have enormous costs and would have limited results. Another possibility is to quarantine only persons with symptoms of AIDS. However, this approach would not isolate the majority of infected persons. A final approach would be to quarantine only infected individuals in high-risk groups, such as homosexual and bisexual males, intravenous drug users, and female prostitutes. However, this strategy, based on predictions of future behavior, would discourage members of these groups from seeking testing or treatment. More appropriate than quarantine is increased research, education, and efforts to address intravenous drug use. Notes and 27 references.