The authors aimed to examine the association between diurnal temperature range (DTR) and daily mortalities due to cardiovascular disease among people aged 65 years and older in Hong Kong, China. The authors used generalized additive model to regress daily mortalities of the elderly due to cardiovascular disease on DTR and daily concentrations of air pollutants from 1997 to 2002. They also tested the effects of different lag days of DTR on mortality. Results indicate significant associations between cardiovascular mortality and DTR at lag day 1 and at lag clays 0-1 to 0-5. The largest effect was at lag days 0-3 (relative risks = 1.017; 95% confidence interval = 1.003-1.031). The authors recommend that special attention be paid to the elderly population to protect them from excessive diurnal variations in temperature.