The Trade Competition Act (TCA) applies to all enterprises and business activities in Thailand, with certain enumerated exceptions, such as state enterprises, cooperatives, agricultural and cooperative groups, and government agencies. If you are a business operator in Thailand, especially a market-dominant operator, the TCA governs how you do business. The TCA regulates abuse of dominance, anticompetitive agreements, unfair trade practices, and interference with consumer purchases from foreign suppliers. Upon passage of a ministerial notification setting review thresholds, the TCA will also allow for the review of mergers by the Trade Competition Commission. This article will focuses primarily on two areas of concern for commercial entities—abuse of dominance and anticompetitive agreements.