Objectives: To evaluate the all-cause (ICD-9 000-999) and cardiovascular diseases (ICD- 9390-459) mortality risks associated with regional ambient temperatures in Taiwan between 2000 and 2008. Methods: We applied the distributed lag non-linear model to estimate the 8-day cumulative mortality risks associated with high temperatures during the hot season (May-October) and 26-day cumulative mortality risks associated with low temperatures during the cold season (November-April) in 7 study areas. Area cause-specific mortality risks were estimated in association with daily average temperatures at Z±1 and ±2 and by study season. Results: The mortality risks in Taiwan were greater from low temperatures than hot temperatures, especially for mortality from cardiovascular diseases. The mortality risk associated low temperatures was highest in the Taoyuan-Hsinchu-Miaoli area, with relative risks of 2.21 (95% confidence interval [CI]: 1.33-3.67) for all-cause and 4.09 (95% CI: 1.39-12.03) for cardiovascular diseases. High temperatures also elevated the all-cause mortality, but not cardiovascular diseases mortality, in the Yunlin-Chiayi-Tainan and Kaohsiung-Pingtung areas. In contrast, extremely high temperatures were associated with cardiovascular diseases mortality in the Hualien-Taitung area only. Conclusions: Cumulative all-cause and cardiovascular diseases mortality risks for high and low temperatures are various among regions in Taiwan. This study provides the reference for a temperature-health warning and response system for the local health authority in Taiwan.