Vietnam is one of the countries being impacted greatly from climate change. Besides of influencing the natural environment and human's living condition,. climate change has created immense changes to diseases and living features within the biosphere. This study is aimed at: 1) identifying the correlation between some climatic factors and the number of dengue fever cases reported in Hanoi from 2009 to 2011. 2) building a forecast model for dengue fever. Based on biometric regression analyses on reported dengue cases and other climatic factors during the period 2009-2011, three forecast models have been determined. The analysis results have pointed out high possibility of dengue fever during the period from June to Deaember, while temperature, rainfall, evapo-transpiration gained the highest values. The model with 2-month lag-time data provides better forecast results than other models which use recent data.