Acellular pertussis vaccines contain antigen components of B. pertussis, usually lymphocytosis promoting factor (LPF) which is also called pertussis-toxin (PT) or pertussigen, filamentous hemagglutinin (FH) and, eventually, agglutinogens 2 and 3. Acellular vaccines are being used in Japan since 1981. Several Phase II studies have been performed and showed a better tolerability than whole cell vaccines and antibody responses of at least equal magnitude. In some of these studies good protection rates were observed. The latter were not satisfactory in a Phase III study in Sweden. This study, however, might cause some criticism in as much as only 2 vaccine doses were given and a control group with whole cell vaccine was missing. Moreover, the significance of bacterial infections in vaccinated children is doubtful, similar observations have not been made in other trials nor in Japan since introduction of the vaccine in 1981. Preliminary results of our own study with a newly developed acellular vaccine which has been permitted by the Austrian Drug Commission have shown good tolerability.