Several epidemiological studies have provided evidence that exposure to auto vehicular traffic increases the prevalence of bronchitis, cough and deficits in lung function and may exacerbate pre-existing asthma, especially in children. The aim of this study was to investigate the role of road traffic pollution on respiratory health in a large sample of Italian school children. Eighteen percent of the SIDRIA-2 sample reported high traffic density in the zone of residence; 60% and 20% of subjects reported a very frequent transit of cars and lorries, respectively on the street of residence. High frequency of lorry traffic in the street of residence was associated with significantly increased risks for chronic cough or phlegm and sinusitis symptoms. These results, confirming previous findings (SIDRIA, 1994-95), show that children living near streets with intense traffic of heavy vehicles are at higher risk for adverse respiratory effects, especially for productive cough.