Academic faculty members in medical schools rarely receive formal instruction in basic pedagogic principles; nevertheless many develop into competent teachers. Perhaps they acquire tacit knowledge of these principles with teaching experience. This study was designed to assess clinical teachers' tacit knowledge of basic pedagogic principles and concepts. The authors developed a multiple-choice question (MCQ) exam based on 20 pedagogic principles judged by a panel of education experts to be important for clinical teaching. Three groups of clinician-educators sat the test: (1) clinicians with advanced education training and experience; (2) internal medicine specialists; (3) surgical specialists. All four groups of clinicians-educators passed the test, indicating that they possess a reasonable tacit knowledge of basic pedagogic principles. Those with advanced education training performed much better than members of the other two groups while specialists and residents working in teaching hospitals outperformed specialists from non-teaching hospitals. It is possible that converting this tacit knowledge to explicit knowledge may improve individual teaching effectiveness.