Besides the classical theories of the firms as complete or incomplete contract theories, in the last decades there were developed some new theories bringing new perspectives and approaches. Among these new perspectives we are presenting in this paper the evolutionary theory of the firm, the importance of resources and knowledge, and game theory. According to evolutionary theory the most important element for a firm is the company itself and its specific assets (physical and human). Evolutionist theories, in their diversity, are interested in issues such as the effects of changes in the long run within the firms, in terms of products, processes, decisions, analysis of the determinants of success. Resource and knowledge -based theories try to find a common point between transactions and organizational management analysis, focusing on development issues within companies, the importance of business strategy and achieving competitive advantages. Finally, cooperative game theory sees the firm as a coalition of various parts that compose it, emphasizing the importance of cooperative relations between employees and shareholders, risk sharing and effective collective skills, knowledge and funds using.