In the absence of definitive legal precedents, family therapists must decide whether to warn sexual partners of HIV-positive clients when clients themselves refuse to do so. Deciding whether to break confidentiality reaises both legal and ethical issues. Legally, the Tarasoff ruling requires therapists to warn potential victims of illegal dangers posed by clients but does not require therapists to warn potential victims of dangers posed by their clients' legally permissible actions. unless the behavior of the seropositive client is proscribed by state law, warning the clients' partners does not fall within the scope of the Tarasoff ruling. Ethically, therapists must negotiate and adhere to a disclosure policy that balances considerations of respecting autonomy, maintaining integrity (avoiding fraud and betrayal), benefiting clients, and fostering responsibility. Some therapeutic and ethical aspects of these considerations are discussed.