The internist, expected to play an increasing role in occupational medicine, is likely to encounter ethical dilemmas in treating working patients, including those involving loyalty, confidentiality, reporting known or suspected occupational hazards and diseases, and maintaining awareness about occupational health factors. Many of these dilemmas become realized when the internist integrates occupational health services into general internal medicine practice, particularly when these services are important to employment decisions, such as the preemployment and periodic examinations. Appropriate responses to these dilemmas and the situations from which they arise can be formulated, based on accepted ethical and legal principles.