Book excerpt: Diagnostic errors are important in all branches of medicine because they are an indication of poor patient care. As the number of malpractice cases continues to grow, radiologists will become increasingly involved in litigation. The aetiology of radiological error is multi-factorial. This book focuses on (1) some medico-legal aspects inherent to radiology (radiation exposure related to imaging procedures and malpractice issues related to contrast media administration are discussed in detail) and on (2) the spectrum of diagnostic errors in radiology. Communication issues between the radiologists and physicians and between the radiologists and patients are also presented. Every radiologist should understand the sources of error in diagnostic radiology as well as the elements of negligence that form the basis of malpractice litigation.