A study on 132 families where a lambliasis case was diagnosed is presented. An epidemiological investigation in each family was made; faeces were analyzed to find Lamblia carriers. The total number of investigated persons--lambliasis cases excluded--was 405; 30 of them (7.4%) were positive. Between people younger than fifteen the percentage of positive test was 14.7%, while over this age the rate of affectation was 4.2%. There is an statistic association with the assistance to child school. No correlation with sex or another determinant factors was found. Carriers treatment was successful in 96.1%.