At the Swiss Serum and Vaccine Institute, Berne, a highly purified rabies vaccine presenting a high content of effective rabies virus glucoprotein antigen has been developed. The new vaccine is derived from embryonated duck eggs (PDEV). Immunizations performed according to the post-exposure schedule recommended for potent rabies vaccines by the WHO (6 injections on days 0, 3, 7, 14, 28 and 90) already induce protective antibody titers on day 14 (greater than 1 IU/ml). Use of the latest radioimmunological methods did not reveal the presence of myelin basic protein in the new rabies vaccine. Due to improvements of its preparation the rabies vaccine PDEV is an economical and highly efficient vaccine involving only a very remote risk of post-vaccinal encephalitis.