Objetivo:Objetivo: Avaliar a prevalência de morbidade respiratória entre crianças expostas ao fumo passivo e determinar os efeitos do fumo ambiental no sistema respiratório inferior e superior dessas crianças, na cidade de Fortaleza, Ceará, Brasil. Respiratory morbidity among passive smoking children Objective: Objective: To study the prevalence of respiratory morbidity among passive smoking children and to determine the effects of environmental tobacco smoke in the upper and lower respiratory system of these children in the city of Fortaleza, Ceará, Brazil. Cases and method:Cases and method: This is a cross sectional study of 1,104 children under the 5 years old. Information about respiratory symptoms and illnesses of the children, family history of respiratory diseases, smoking habits of household members and housing conditions were assessed by a questionnaire addressed to the children's parents. Results:Results: Among the 1,104 children, 558 were males and 546 were females. Respiratory morbidity was greater in the children exposed to environmental tobacco smoke than in those who were not exposed (82% vs 74%). Regarding the lower respiratory tract, the most frequent complaints were wheeze (57.7%; OR = 1.32; IC 95%: 1.04-1.68), dyspnea (43.8%; OR = 1.56; IC 95%: 1.22-1.99), asthma, bronchitis or pneumonia (29.4%; OR = 1.31; IC 95%: 1.00-1.71).As to the upper respiratory tract, rhinitis was the most frequent complaint (38.1%; OR = 1.46;ARTIGO ORIGINAL