The authors investigated the effects of ambient air pollution on hospital admissions in Brisbane, Australia. The authors used the Air Pollution on Health: European Approach protocol to examine the effects of particles, ozone, sulfur dioxide, and nitrogen dioxide on daily hospital admissions for asthma and respiratory, cardiovascular, and digestive disorders (control diagnosis) that occurred during the period 1987-1994. Ozone was consistently associated with admissions for asthma and respiratory disease-with little evidence of a threshold. In two-pollutant models, the ozone effect was relatively unaffected by the control for high levels of other pollutants. Particulate pollution (measured by nephelometry) was associated positively with admissions for respiratory disease and admissions for asthma in summer, whereas a negative association was observed for cardiovascular admissions. Although sulfur dioxide was associated significantly with admissions for respiratory and cardiovascular disese, a significant association was also found for the control diagnosis of digestive disorders. No significant associations were found for nitrogen dioxide over the study period, although significantly positive seasonal interactions were found for asthma and respiratory disease in autumn, winter, and spring. It was concluded that current levels of ambient air pollution in Brisbane make a significant contribution to the variation in daily hospital admissions for asthma and respiratory disease.