According to the authors, clinical medicine in the tropics, as compared with that of the temperate zones, differs less in the particular diseases with which it deals than in their relative frequency, their different groupings, and the difference in the clinical courses which they run. The authors, however, fail to note that, in a few instances at least, the geographic distribution of certain intermediate hosts of pathogenic parasites of man restricts certain diseases, such as clonorchiasis and African trypanosomiasis, to the tropical or subtropical regions. However, even these restrictions are not zonal but rather geographic or even ecologic, and are correlated with a high degree of host specificity. The phrase "tropical disease" is therefore somewhat of a misnomer, but the results of the practice of medicine in the tropics tend increasingly to demonstrate the importance of the climatic factor in the incidence, clinical picture, treatment and prognosis of particular diseases.