Abstract. The steel industry is an important basic industry to the economic growth of developing countries. Steel is a primary raw material for many products downstream in the supply chain. In this paper, we study important factors in the steel industry in Thailand. The relations among the factors are analyzed using a method called DEMATEL. There are totally 11 important factors. The analysis shows that there are three groups of factors: causal, affected, and independent ones. Since the causal factors affect other factors, they should be paid attention very closely. The analysis shows that there are four causal factors which are large domestic market size, favorable government policies, high labor skill, and well planned production schedule. The other factors, however, are also important to the industry even though their roles are different. Strategies are then formulated based on the roles of the factors to enhance the competitiveness of the Thai iron and steel supply chain.