Objective: Professional guidelines recommend that physicians discuss confidentiality with adolescents. This study investigates physicians' practices regarding assurances of confidentiality to adolescent patients.Methods: A mail survey was completed by 786 board-certified physicians practicing Family Practice, Internal Medicine, Obstetrics/Gynecology, or Pediatrics in California. Outcome Measures: Physicians were asked the (1) percentage of adolescents with whom they discuss confidentiality and (2) content of their assurances of confidentiality. A clinical vignette assessed (3) physicians' knowledge of legal guidelines regarding confidential treatment of adolescents.Results: Physicians reported discussing confidentiality with, on average, 53% of their adolescent patients. While 21% of physicians directly discussed confidentiality with all adolescents, 11% did not discuss confidentiality with any adolescent patients. Using hierarchical linear regression to control for other physician demographic and practice factors, female physicians were more likely to discuss confidentiality than male physicians (p<.001), and Gynecologists were more likely to discuss confidentiality than other primary care physicians(p<.001). Among physicians who discussed confidentiality, 64% assured unconditional confidentiality and 36% assured conditional confidentiality. When asked about legal guidelines regarding the management of a 15 year old patient with a sexually transmitted disease, 63% of physicians responded correctly, 5% responded incorrectly, and 31% were unsure of management guidelines. Physicians who were knowledgeable about legal guidelines were more likely to discuss confidentiality with adolescent patients (p<.001). Conclusions: Physicians do not consistently discuss confidentiality with their adolescent patients. The majority of physicians who discuss confidentiality with adolescents assure unconditional confidentiality, which is not consistent with professional guidelines or the legal limitations of confidentiality.