This study is the first attempt to investigate mortality seasonality and weather-mortality relationships in Hong Kong from 1980 to 1994. Monthly mortality data from all causes of death, neoplasm, circulatory and respiratory diseases were obtained from the Census and Statistics Department and the weather data were obtained from the Hong Kong Observatory. Regression analyses and ANOVA were employed. Significant winter peaks in sex specific and total deaths from all causes, circulatory and respiratory diseases were ascertained. Cancer mortality, however, was not seasonal. Mortality seasonality only existed in age groups 45-64 and > or =65. For the impact of weather on mortality, no significant relationship between weather variables and cancer mortality was observed. A significant negative association between minimum temperature and a positive relationship between cloud and deaths were found. This suggests that colder and cloudy conditions may heighten mortality. Wind was discovered to have a negative association with mortality. This finding revealed that the stressful effect of wind on mortality was negligible. There was no apparent sex difference. Deaths from the younger age groups (0-24 yr old) were not weather related. Weak weather connection with mortality for age group 25-44 was discovered, with Adj r2 values ranging from 0.05 to 0.07. The elderly (age > or =65) were more vulnerable to weather stress and strong weather-mortality relationship was uncovered, with Adj r2 values from 0.36 to 0.66. These results are important information for formulating public health policies.