||This thesis focuses on the behaviour of firms when choosing among multiple markets one to enter. This situation occurs frequently during expansions of firms or introduction of new products. The model used is similar to the model of a static entry game by Bresnahan and Reiss (1990), which was applied on single markets under various assumption to model the impact of market structure. In the thesis a similar discrete-choice model is formulated and studied under multiple markets, to determine the market and output a firm chooses. An entry model with heterogeneous products, 2 firms and N markets is studied and compared to findings about single market entry. To test various characteristics of the structure of markets a simple computer program is used to simulate market entry.