The scientific work of Walther Birkmayer is grounded on his ability to turn what was often a mass of clinical details into the basis for a hypothesis for a new therapeutic approach toward solving the problems of a patient's illness. Birkmayer first became known when, during the Second World War, he built up a clinic for brain injuries in Vienna, in which over 3000 patients were treated. The study of changes in the autonomic functions of the nervous system in these patients as well as the problems of rehabilitation were published in a monograph, "Hirn- verletzungen". Consequently, this was his major scientific interest during the post-war years. His book, "Klinik und Therapie der vegetativen Funktionsstorungen" published with W. Winkler, brought Birkmayer recognition in the German-speaking world. In 1954 he took over the Neurological Department of the Geriatric Hospital of Vienna in Lainz, where he remained until his retirement in 1975. International acclaim followed his breakthrough with the clinical application of L-DOPA in Parkinson's disease. Birkmayer, as a strong adherent to the scientific interpretation of neurological and psychiatric disease, has encouraged multidisciplinary research. This is reflected in his establishment of the former Ludwig Boltzmann- Institute of Neurochemistry, in which pharmacological, biochemical and histopathological research into neuropsychiatric diseases was performed under one roof. Further to his initial work on L-DOPA, Birkmayer has been in the forefront of supplementary parkinsonian therapy using enzyme inhibitors: benserazide in 1967, unselective monoamine oxidase inhibitors in 1962 and deprenyl in 1975.