Larval surveillance during this study was important to find out the extent of prevalence of vectors in a locality. House index was used in this study to help stratifying DHF risk areas for further control and monitoring of the vector population in defined areas. House index from our study indicated a high risk of DHF transmission. The WHO standard for high DHF risk areas was 5 % house index. This indicates a high risk of DHF transmission in Nakhon Si Thammarat Province, Thailand. Our results showed 59.68% house index for Ae. aegypti larvae and 62.50% house index for Ae. albopictus at Muang Nakhon Si Thammarat. Promprou et al. (2007) studied six districts in Nakhon Si Thammarat and found that all six districts had higher house index than WHO standard for high DHF risk areas. As we are GLOBE students, we should launch some campaign to raise some awareness on mosquito larvae in the area.