Background: This paper examines the short-term health effects of air pollution on daily hospital admissions in Australian cities (those considered comprise more than 50% of the Australian population) for the period 1996-99. Methods: The study used a similar protocol to overseas studies and derived single city and pooled estimates using different statistical approaches to assess the accuracy of the results. Results: There was little difference between the results derived from the different statistical approaches for cardiovascular admissions, while in those for respiratory admissions there were differences. For three of the four cities (for the other the results were positive but not significant), fine particles (measured by nephelometry--bsp) and nitrogen dioxide (N[O.sub.2]) have a significant impact on cardiovascular admissions (for total cardiac admissions, RR=1.0856 for a one-unit increase in bsp ([10.sup.-4].[m.sup.-1]), RR=1.0023 for a 1 ppb increase in N[O.sub.2]). For three of the four cities (for the other, the results were negative and significant), fine particles, N[O.sub.2] and ozone have a significant impact on respiratory admissions (for total elderly respiratory admissions, RR=1.0552 per 1 unit ([10.sup-4].[m.sup.-1]) increase in bsp, RR=1.0027 per 1ppb increase in N[O.sub.2], RR=10014 per 1 ppb increase in ozone for elderly asthma and COPD admissions). In all analyses the particle and N[O.sub.2] impacts appear to be related. Conclusions: Similar to overseas studies, air pollution has an impact on hospital admissions in Australian cities, but there can be significant differences between cities.