The quantification of the relationship between daily mortality and air temperature, as a fundamental policy is essential to enhance the accuracy of the warning system of decrease and increase of temperature. The objective of this study was to investigate the relationship between temperature and death rate in Tehran during the period (2002-2005) by combining statistical and geographic information system methods. The Results of this study indicate that there is a strong and meaningful correlation between air temperature and death rate especially between monthly averages ones. The highest rate of mortality has occurred in the cold months of the year (December, January and February). and as the temperature decrease, the death rate increase. The increase in death rate caused by cardiovascular, respiratory and stroke diseases in the cold months of the year, bears proof to this matter. Among 22 zones of Tehran, zones 9, 6 and 12 have got the highest number of death occurrence. The correlation between daily death rate and daily temperature averages was V-shaped. Results of this study confirm some previous findings such as those in Moscow, United States, Hong Kong, Madrid, Athens and Shanghai. Temperature minimum mortality for Tehran was calculated as 28.5°C. The obtained results also indicate that the higher was the temperature difference from the Temperature minimum mortality, the more the death rate increased. Finally, the optimum policies for the mitigation of mortality in Tehran are presented