A survey of knowledge and opinions of population about etiology and treatment of diseases in the community ("palafitas" area of São Luís, MA) was done. The results were: the major percentile (43.6% and 17.8%) of correct or parcial correct knowledge; 74.0% of the population used "pharmacy medicine" to treat the disease, although they prefer (50.6%) to be treated at home; 62.1% of population used medical treatment although 36.7% said that the family gave the treatment