The microbiological and parasitic risks associated with the tremendous increase in the tourist traffic from West Germany and Austria into warmer countries are considerable even in the case of shorter stays, as has been confirmed by observations made on those returning from such areas. The most important groups of diseases -- worm diseases, amoebiasis, and malaria -- have maintained this ranking in Central and South America; in Africa, especially in the east, the incidence of malaria tropica is increasing. The proportions for Austria show that even numerically there are no great differences compared with West Germany. It seems that, as far as malaria is concerned, efficient prophylactic measures and reliable information are absent; at any rate, the cases of malaria tropica were severe and in the main no prophylactic measures had been taken. With the exception of Japan, the risk of hepatitis in all warmer countries and in the East in general is many times higher than in the Federal Republic of Germany and the length of stay is partly a determining factor. For instance, the risk of hepatitis is roughly forty times higher in India. All figures shown in this survey are supported by tables, literature, and personal experience.