Ethical dilemmas involving confidentiality issues are frequently encountered in occupational medicine. The occupational physician faces a unique challenge because in many circumstances, a physician-patient relationship, in the ordinary or legal sense, may not exist. The occupational physician often faces a conflicting interest between the employees' desire for privacy and the employer's legitimate need to know. The occupational physician must carefully balance these interests for the benefit of society and the parties involved. Occupational physicians also work in a wide variety of practice situations, and the ethical and legal duty of confidentiality may vary substantially with these roles. This article provides an overview of the ethical and legal requirements of confidentiality in the workplace. The constitutional, statutory, and common law framework governing the treatment of employee medical information, as well as defenses to liability, are discussed. Recent legislative changes such as the Americans with Disabilities Act, and new challenges such as the proper handling of HIV information, present unique confidentiality problems.