An Introduction to clinical trials is a concise step-by-step guide to the principles and practices of clinical trials for those studying clinical trials or new to working on one. Clinical trials are critical to the progress of medicine and improving healthcare, as they evaluate whether new treatments and interventions work. They are also complex, multidisciplinary projects that integrate science, ethics, and legal requirements in the conduct of medical research. Starting with the research question, An Introduction to clinical trials explains study design, sample size determination, study set-up, study conduct, statistical analysis, and dissemination of the results. The book primarily focusses on randomised controlled trials as the "ultimate" clinical trial. It demystifies the terminology used in clinical trials research and presents the underlying scientific and statistical concepts. Real-life examples are used throughout to bring concepts to life. Written by an experienced medical statistician, An Introduction to clinical trials will benefit readers of all backgrounds, from postgraduate and medical students, trainee doctors and healthcare professionals to others working on clinical trials in a professional capacity. This book aims to help readers gain a fuller and more rounded understanding of clinical trials.