Since the end of the 90s, Sao Paulo has seen countless numbers of health care organizations extending their business scope. According to the latest researches from Agencia Nacional de Saúde Suplementar (ANS) and Instituto Brasileiro de Geografia e Estatística (IBGE) and to recent academic papers, there have been increases in supply and demand for private health care services in Brazil in the last years. In what follow, advances of new health care services and the growth in competition among health care providers, mostly in wealth metropolitan areas. This dissertation addresses the use of common concepts of market entry for a health care organization and investigates three distinct strategies of market entry carried on by this organization. The dissertation’s main propose is to answer how these market entry strategies played a role at the birth of enterprises’ resources and capabilities and their performances. Regarding this environment, the present work reviews the literature of Diversification, Market Entry and Resource-based View of the Firm, and also analyzes the Brazilian Health System. The field research is undertaken at Fleury S.A., based on a case study supported by interviews with top executives. Three enterprises - Check-up, Day-Hospital and NKB - are studied in deep and showed different entry characteristics, which varied according to their heritage and to the strength of their ties to Fleury. The analysis of the Fleury Case shows that strategies of market entry may improve the likelihood of new enterprises success, particularly when potential entrant has a clear understanding of its resources and capabilities and the needs of the potential market. On the other hand, the lack of experience at the potential market, mislead analogies and overconfidence are reported as the main causes of inappropriate market entry. Another important finding is the learning trajectory that follows the enhancement of company’s resource and capabilities base.