Tetanus is still a major health problem in developing countries and still occurs in countries with a high medical standard. To guide planning of future prophylactic programs, incidence and mortality from tetanus in Denmark previous and present prophylactic efforts have been studied. Incidence and mortality from neonatal tetanus decreased in the thirties probably consequently to social and hygienic improvement, and a very marked decrease coincided with the introduction of vaccination against tetanus in 1947. Since 1970 no case of neonatal tetanus has been observed. Mortality from non-neonatal tetanus was reduced markedly in 2 steps, coinciding with an increased use of tetanus antitoxin around 1930 and the introduction of vaccination respectively. The effect of routine vaccination in childhood from 1950 was especially prominent. Tetanus in childhood is now nearly eradicated. A survey of all hospitalized cases of tetanus 1978-1982 showed that the majority of patients were incompletely or never vaccinated, but 10% had a history of complete vaccination. The majority of cases developed from minor posttraumatic lesions, of which only 41% had been professionally treated, and 13% developed from non-traumatic lesions. It is concluded that vaccination programs offering continuous protection are needed for a complete eradication of tetanus. Fatality remains high, in the present series 9.4%, and is mostly due to cardiovascular manifestations.