Thorium (²³²Th) concentration was determined by Instrumental Neutron Activation Analysis (INAA) in animal origin food groups  widely consumed by population residing in monazite rich area of Tamil Nadu, India. The annual intake was evaluated based on market basket study method for female and male population for different age groups. Annual committed effective dose due to ²³²Th intake from the ingestion was evaluated for different age groups of individuals, using the ICRP ingestion dose coefficients and annual consumption rate obtained from National Nutrition Monitoring Bureau (NNMB). Annual intake values of ²³²Th for adult members of the population were obtained from food items as, fish from 0.2 to 0.8; flesh food (meat, beef and chicken), from 0.03 to 0.12; and milk from 0.2 to 0.3 Bq year^-1. The total annual internal dose resulting from ingestion of radioisotope in these food groups was 0.2 μSv year^-1 for male adult population.