To assess the impact of weather on human mortality, particularly among elderly people and people with diseases, the authors conducted an ecological study in Brisbane, Australia. Correlation and autoregressive integrated moving average (ARIMA) regression analyses assessed the relationship between weather and mortality in the general population and the elderly population, (65 years of age aid older) over the period 1986-1995. In the summer, both cardiovascular diseases and all-cause mortality in the elderly population had significant positive correlations with monthly temperatures. In the winter, negative correlations were found between monthly mean maximum temperatures and cardiovascular-disease mortality, and between. monthly mean minimum temperatures and respiratory-disease mortality. Regression models were developed for various target populations and produced similar results.