Objectıve: Little evidence is available on the association between ozone exposure and health in Campo Grande, Brazil. In this study, we aimed to examine the effects of surface ozone concentrations(O3) on respiratory morbidity in Campo Grande, Brazil during the period from January 1st, 2008 to December 31st, 2011. Methods: Daily data on respiratory hospital admissions, O3, mean temperature, and relative humidity were collected at Campo Grande, Brazil. A Poisson time series model was used to examine the effects of O3 on hospital admissions, while controlling for seasonality,long-term trend, temperature and relative humidity. A distributed lag non-linear function was used for O3, temperature, and relative humidity. We examined the effects of O3 on different age groups (0 - 4 years, 5 - 60 years and >60 years). Results: The ozone-respiratory morbidity relationship was non-linear, with a threshold at 13 ppb (less than 25% percentile of ozone distribution).We estimated the relative risk of hospital admission at 75% percentile of O3 distribution compared with associated with 25% of percentile of O3 distribution. The O3 effect on respiratory morbidity was delayed by two days and lasted for 4 days for all age groups except people aged 5 - 60 years. Children and the elderly were much more vulnerable to ozone pollution than people aged 5 - 60 years. Conclusıons: This study suggests that ozone pollution has negative impacts on respiratory diseases in Campo Grande, Brazil. Children and the elderly were susceptible to O3 exposure.These findings should be used to develop policies for protecting people from O3 pollution.