This paper wishes to point out to its readers the importance of the role played by the national parks in the development of tourism in Croatia. At the same time, it also wishes to point out the need for environmental protection of Croatia’s protected areas. The work’s goal is to indicate at the problems that the development of tourism creates in national parks, as well as to offer sustainable development solutions for tourism in national parks. In this paper all Croatian national parks are first separately studied, following which an examination is made of the problems that concern all of the parks. Conclusively, tourism is what causes the biggest threat to devastation and disturbance of the environment. Even in the areas protected by law it can have dire consequences. However, quality management and control of these areas can prevent the negative aspects of tourism and, at the same time, contribute to its positive effects. The author wishes to emphasize how everybody should be aware of the need for environmental protection, tourists and local residents equally. The research is organised in several sections. The introduction briefly describes the paper’s theme, goals and purpose. The first part of the research defines national parks, describes the history of their formation and the specific problems of Croatian national parks. The second part includes a detailed description of every Croatian national park. The third and last part highlights the national parks’ role in tourism development, briefly talks about an ideal touristic offer of a national park and discusses the relationship between tourism and environmental protection.