Kerala State in India was gripped by a renewed and widespread outbreak of Chikungunya virus (CHIKV) infection during 2007. Here, we report the A226V mutation in the glycoprotein envelope 1 (E1) gene of the virus among isolates collected from the three worst-affected districts of the state during this outbreak. This mutation had already been suggested to be directly responsible for a significant increase in CHIKV infectivity in Aedes albopictus. The badly affected districts in Kerala State during 2007 have abundant rubber plantations, which supported prolific breeding of Ae. albopictus mosquitoes. The abundance of Ae. albopictus in the region and molecular evolution of CHIKV may be contributing factors for the renewed epidemic of chikungunya fever during 2007.