India is a major emitter of mercury to the environment, mainly due to emissions from coal-fired power plants. Consumption of fish and rice, two important pathways for human exposure to mercury, is particularly high in South India. Here, we report concentrations of total mercury in hair (THghair) in 668 participants from South India. Three cities were covered: (i) a city on the east coast with four active coal-fired thermal power plants (Nellore), (ii) a city on the west coast with no major mercury source (Vasco da Gama), and (iii) a metropolitan city in the interior with no major mercury source (Hyderabad). Geometric mean of THghair of the entire study population is 0.14 µg/g (95% confidence interval, CI: 0.13-0.15 µg/g). Significant predictor variables are age, fish consumption, and occupations such as dental studies, subsistence fishing, and artisanal goldsmithing (which is different from artisanal scale gold mining). Our results support the hypothesis that people living in a city with active coal-fired power plants may have higher THghair than those in cities with no major mercury source.