This book is intended to be a reference for scientists and engineers interested in applying type-3 fuzzy logic and fractal theory techniques in medical diagnosis. In this book, a new model based on type-3 fuzzy logic and fractal theory for applications in medical diagnosis is presented. The main idea is that a higher type and order of fuzzy logic can help in solving various diagnosis problems and find better results. In addition, fractal theory is also employed for enhancing medical diagnosis. In this regard, several hybrid intelligent methods are offered. In this book, the authors test the proposed methods using several medical diagnosis problems, like diagnosis of problems in the brain, hearth, lungs, and others. The authors can notice that when type-3 fuzzy systems are implemented to model the behavior of systems, the results in diagnosis are enhanced, because the management of uncertainty is better. For this reason, the authors consider in this book the proposed methods using type-3 fuzzy systems and fractal theory to improve the diagnosis in complex medical problems.