The rich body of scholarship on the British-owned Anglo-Iranian Oil Company (AIOC) has made invaluable contributions to an elucidation of the political and economic dimensions of the oil company’s power in Iran and the lived experience of Iranian oil workers. It has also left room for investigations into the ways in which the oil company’s operations were shaped by, and in turn shaped, the environment in which it developed. This paper explores the interrelations between the emergent oil industry and the environment of southwest Iran through the lenses of sickness and health. Matters of health and unhealth were, from the inception of oil exploration, intimately bound up in the emergence and success of oil imperialism in Iran, mandating the Company’s investment in public health programs and a robust modern medical infrastructure. In its examination of the climatic and disease environment of southwest Iran, this paper addresses three main topics pertaining to the rise of the oil industry and corporate colonialism in Iran: 1) environmental dangers to the health of Iranian and Indian labor and European staff, and the AIOC’s response to those dangers. Such hazards included the heat and endemic and epidemic diseases; 2) British perceptions of the environment of southwest Iran as threatening to the physical and mental health of European employees and their families. Exploring the discourse of climatic peril places the development of the oil company’s mostly British enclave within the context of European scientific debates about the suitability of the colonization of the “tropics”; and 3) the impact of petromodernity on the disease environment of the region, including the flow of diseases in the Persian Gulf and the frequency of disease epidemics.