A Turkish dermatologist named Hulusi Beh~et defined a syndrome, the major symptoms of which comprise oral ulcers, genital ulcers, eye lesions, and skin lesions, as a specific disease in 1937, and the disease was named Beh~et's disease after him. Since then, there have been more than 4500 reports presented world­ wide on this disease showing that Beh~et's disease is no longer rare. Because Beh~et's disease is clinically dynamic and its clinical symptoms are various and their spectrum very wide. However, there are insufficient pathognomic laborato­ ry data for the diagnosis of Beh~et's disease, so it is with great difficulty that Beh~et's disease specialists diagnose the disease based only on their clinical expe­ rience. We have therefore collected data from more than 5500 living Beh~et's disease patients whom we have seen, and we have brought together data from other nations and other continents. We hope the result is a clinical guide for those inter­ ested in Beh~et's disease. To improve the accessibility of the information, this text­ book was made in a photo-monography style with an atlas style, and we have tried our best to make our sentences short and clear. We are grateful to the many scholars worldwide whose contributions have added greatly to the value of this textbook. We are especially grateful to the staff of Springer-Verlag who have shown deep kindness and patience. Special thanks to Ms. Heather Yu for helping us in writing this monograph in English, and Mr. Jung-Woon Lee for his assistance.