It was originally my idea to prepare a book which would enable students to have presented to them in intimate relation the laboratory and clinical aids to the diagnosis of tropical diseases. I was forced to abandon this plan as it did not seem possible to take up clinical diagnosis prior to the obtaining by the student of a comprehensive knowledge of the facts in connection with each separate tropical disease. There was not the same difficulty attaching to a book exclusively devoted to the diagnostic methods of the laboratory so that in 1908 a laboratory manual was published. More recently it has occurred to me that my methods in teaching tropical medicine from the clinical rather than the laboratory standpoint might be of assistance to those who are interested in this very important branch of medicine. When we consider that a knowledge of malaria, blackwater fever, amoebic dysentery, bacillary dysentery, liver abscess, pellagra and hookworm disease is just as important for the medical man in the Southern States of the United States as for the physician in tropical colonial possessions, it will be realized that there is more of a practical side to tropical medicine than is usually admitted. Although this is intended as a companion volume to the one on laboratory methods yet, in order to make it complete in itself, there has been prepared under each disease a paragraph dealing with the laboratory diagnosis of the disease under consideration. Furthermore, under the sections on the blood, faeces and urine in the diagnosis of tropical diseases, the laboratory methods which are of practical application have been given. The chief feature of the book is in presenting in Part II the clinical side of tropical diseases from a standpoint of the signs and symptoms of these diseases which are connected with anatomical or clinical groupings rather than from the side of the individual disease. Thus in Chapter XLIV the diagnostic points which may be obtained from a study of the temperature chart are given while in Chapter LII the neurological manifestations, which may be noted in various tropical diseases, are presented. In Part I each individual tropical disease is treated as taken up in any of the well-known books on tropical medicine. It has seemed to me, however, that the paragraphs on epidemiology and prophylaxis should receive especial attention. Again, in order to bring out more strongly the symptomatology of each disease, I have followed the paragraph on symptomatology in general with a section dealing with the symptoms in detail, as shown in a consideration of the circulatory, respiratory, digestive, nervous and other systems. The paragraph devoted to the definition of each important disease has been prepared with a view to giving the reader a brief description of the disease in its clinical and etiological aspects.