The historical perspective of pharmacogenetics is presented to a large extent from a personal view, since I happened to get into this field of science at the time of its beginning, and since pharmacogenetics has remained the backbone of my scientific career. Pharmacogenetics initially emphasized observations of interpersonal variability, but the attention on interethnic differences soon followed. Technical advances led to the identification of many responsible gene alterations in both individuals and in populations. Included is a relatively extensive discussion in which the effects and the different consequences of monogenic (mendelian) and multigenic (multifactorial) variation are compared.