Secondhand smoking is the third evitable death cause worldwide. The objective of this study was to investigate if there is a relation between respiratory diseases and passive tobacco smoking among children from 0 to 5 years of age assisted in a polyclinic of a small city in the state of Sao Paulo. A questionnaire was applied to the guardians of 115 children aged 0 to 5 years assisted at the health unit were interviewed. Studied variables: socio-demographic (child’s and guardian’s ages, guardian’s education and relationship to the child, family income and housing conditions) and clinical (children’s exposure to tobacco, smoking habits of individuals living with the child, family history of respiratory diseases, pathologies associated with secondhand smoking). The information was analyzed by descriptive statistic which showed that 17.39% of the secondhand smoking group presented otitis, 18.26% hissing, 15.65% runny noses and 6.96% eye irritation. In the non-secondhand smoking group, the percentages for diseases were, 7.83%, 6.96%, 5.22% and 4.35% respectively. Children exposed to smoking show higher risk to develop the abovementioned diseases than those who are not exposed.