Book excerpt: ICD-10 is the 10th revision of the International Statistical Classification of Diseases and Related Health Problems (ICD), a medical classification list by the World Health Organization. It contains codes for diseases, signs and symptoms, abnormal findings, complaints, social circumstances, and external causes of injury of diseases. The code set allows more than 14,000 different codes and permits the tracking of many new diagnoses. The U.S. has used ICD-10-CM (Clinical Modification) since October, 2015. This national variant of ICD-10 was provided by the Centers for Medicare and Medicaid Services (CMS) and the National Center for Health Statistics, and the use of ICD-10-CM codes are now mandated for all inpatient medical reporting requirements. This book is for physicians, practice managers and all others who need learn ICD-10. It’s designed for the clinician to learn how to put their diagnosis into a code and not rely on staff or computer software programs to decide it form them. ICD-10 is a complex system of coding and Medicare and third party insurers have been lenient giving providers a year to get used to the coding system. As a result, physicians and their staff have become very complacent regarding proper coding. However, Medicare and third party insurers will soon begin to deny claims which are not coded correctly, which in turn will cost physician groups time and money. This book focuses on Worker’s Compensation and Personal Injury, a very large segment of the healthcare industry and is a new area to ICD-10. The diagnosis coding for injuries is much different than for Medicare or group insurance and unless the physicians and their staff learn how to use it properly, they risk losing income for themselves and worse, they risk losing the case for the patient.