In Nepal, the national and district level cereal production does not reveal adequately food security problem of the people. Although the Dang district, mid western part of Nepal is food sufficient, food security is still a major problem for backward ethnic and caste groups. This study has as its objectives to assess major factors influencing household food security of Tharu ethnic people. A total of seventy two households were randomly selected comprising of twelve villages of Tharu communities. Cereal production, consumption, use and some variables related to food security were among the data collected. The study showed that 32 per cent of the Tharu households were food secure, 35 per cent marginally secure while 33 per cent food insecure. Underemployed labor force, dependency on outsiders land, low income and poor access to the education and employment were found to be their main characteristics of Tharu ethnic people. Tharus’ existing production systems were not sufficient for sustaining their livelihoods. Using ordinary least square regression analysis, the factors influencing food security were found to be access to agricultural extension, adoption of modern rice varieties, higher income sources and reduction of the traditional alcohol making. Understanding potentials and drawbacks of Tharu ethnic cultural system is a prerequisite for improving livelihood and food security.