Volumes 18 and 19 of "Progress in Drug Research" differed from the earlier volumes insofar as they were concerned almost exclusively with problems in the field of Tropical Medicine. The editor and publishers believed that in this way some contribution could be made to the solution of some of the many problems with which the developing countries are burdened. The 20th volume, however, is in the customary form; it contains 17 contributions from various areas of drug research and therapy. Whereas the articles concentrate on a short representation of the progress which has already been made, nevertheless reference is also made to the many unsolved problems within the particular areas. The editor hopes that the 20th volume will not only represent a comprehensive review but will also be of some use in focusing further investigations on problems of medicine that have still not been overcome. The editor would also like to take this opportunity of expressing his gratitude to Dr. A. Naffor carefully working over the manuscripts and correcting proofs. Thanks are also due to the publishers and the printers, Druckerei Birkhauser, especially Dr. A. Birkhauser, Th. Birkhauser and C. Einsele, for their painstaking work on the printing and lay-out of the volume. August 1976 Dr. E. JUCKER Sandoz AG, Basel Vorwort Die Bande 18 und 19 der «Fortschritte der Arzneimitte1forschung» wichen insofern von den vorhergehenden Banden ab, a1s sie fast ausschliess1ich Prob1eme der Tropenkninkheiten behandelten.