Introduction Since graduating from Vanderbilt University School of Medicine in 1955, I have witnessed many changes in the practice of medicine. The most dramatic changes have been the marked increase in specialists and the equally marked decrease in generalists—those physicians and other healthcare professionals in first-contact medical care, by which I mean general internists, family physicians, general practitioners, pediatricians, and nurse practitioners. These professionals see patients as they enter the healthcare system. At this initial point in the process, the nature and cause of a clinical problem is unknown. From my experience in primary care, and from discussions with colleagues, I have found that over 50 percent of primary care patients do not have a definable medical disease. They have complaints or symptoms but no medical disease. Nevertheless, while there may not a definable medical disease to explain every symptom, every symptom has a definable cause. Uncovering these hidden causes takes careful listening, observation, and a collaborative, trusting relationship between professional and patient. Identifying these hidden causes is the essential role of primary care and a major focus of the rules in this book. While this book is aimed mainly at those in primary care, it is meant to be used by all healthcare professionals. Divided into six Little Book of Doc Rules interior.indd 1 1/17/20 2:37 PM The Little Book of Doctor’s Rules 2 parts, it contains rules for developing patient rapport, the diagnostic process, mental status examination, the use of medication, caring for difficult patients, and being a professional. These rules provide guidance on how to learn the details of a patient’s lived life, establish a trusting relationship with a patient, and address the concerns of a patient. By seeing each patient as a human being instead of a collection of symptoms, healthcare workers of every variety can significantly improve the healthcare system, benefitting not only patients but also themselves.