This study re-examines the notions in colonial India about the causes of malaria, specifically discussing the environmental reasons pointed to at the time. It shows how and to what extent some of the widely held ideas of the colonial era on environmental causation contributed to and, at the same time, shaped a kind of environmental awareness, which became a part of medico-social thinking in India. It also adds a new dimension to the thinking on malaria in colonial India by situating the environmental paradigm within a social and economic context.