In order to assess protection level against tetanus, the antitoxin titre was evaluated, by indirect haemagglutination test, in a sample, stratified by sex and age, of 805 subjects of three communes of Tuscany. On the whole the frequency of the serum protected is the 46.1% and it varies according to sex and age: under 20 years it is more than 90%, but it decreases in the successive ages, less in the male sex, probably owing to the vaccination made during the military service. The greatest percentage of immune subjects was observed in the most industrialized area. The less protected professional categories were pensioned people and housewives (25.8%). No differences of serum protection were found between those who practise or do not, recreative activities at the risk (sport, horticulture and gardening). No correlation was observed between the vaccinal anamnesis and the serological test.