The examination by complement fixation test (Machado-Guerreiro) of 545 blood samples randomly assembled in 8 localities of the county of São Lourenço do Sul (RG Sul. Brazii), showed 21 positive (3,85%). There was not significative difference between sex and ethnic group of examined peopie. The prevalence rate was a little higher in periferic areas, adjacent to the endemic áreas of neighbouring counties. Eletrocardiographic anormalities showed a prevalence rate of 57,14% among positive peopie and 26,72% among nega tive. The difference is significant by statistical point of view. Blood pressure, determined in 442 adult peopie, was altered in 154 (34,84%), whithout statisticaily significative difference between sex or ethnic group.