The book "Medical Statistics - Basic Principles" includes the fundamental theory of medical statistics and develops the field of medical statistical methodology in a simple, clear, and understandable way. The 14 chapters of the book cover the essential knowledge of statistical methodology, which relates to observations, experimental interventions on laboratory animals, patients, or healthy individuals. The examples used are numerous, allowing the reader to understand the reasoning that occurs before attempting to solve them. At the end of each chapter, exercises and their answers are provided. The book is aimed at doctors, dentists, biologists, pharmacists, and veterinarians, facilitating their application of appropriate tests and the analysis of data from their research activities.