The aim of this study was to assess immunity levels against tetanus in the areas of 26 health centers in Samsun, Antalya, and Diyarbakir in Turkey in 2000 - 2001. The study group consisted of 2,465 healthy subjects aged 6 months old or above, randomly selected from each age group in the area. Of these, a total of 2,094 (85.0%) serum samples were assayed for tetanus antibody; 716 were from Antalya, 706 were from Diyarbakir, and 672 were from Samsun. The surveys were implemented in three steps: physical examination, interview, and blood collection. ELISA-in-house was used as a screening procedure and a particle agglutination test was used to reassess antibody titers of 1.0 IU/ml or below. It was revealed that 73.5% subjects had the full protection level (>/=0.1 IU/ml) of antibody in Antalya, 59.9% in Diyarbakir, and 75.0% in Samsun, indicating that protection against tetanus was significantly lower in Diyarbakir than in Antalya and Samsun. The results also showed that the percentage of protective levels decreased with increasing age in three provinces and was higher in rural areas than urban areas in Diyarbakir. The study indicates that the immunity levels against tetanus can be considered as satisfactory among children and adolescents but that it is necessary to increase immunity against tetanus among adults through effective vaccination of pregnant women and those in military service and also among people older than 40 years of age.