The book focuses on differential diagnosis in internal medicine. It is intended for medical students and young fellows before their certification in general internal medicine. The book is divided into 10 chapters that contain the differential diagnosis of the most frequent symptoms and clinical or biochemical findings in routine practice. Besides the general symptoms it focuses on the disease manifestations in individual specialties of internal medicine. The unified structure of all chapters includes the definition and characteristics of the symptoms, commentaries to the tables, the way of talking history, physical examination and the choice of both basic and complementary examination methods including the most relevant literature.