The subject of this paper is the interrelationship of sustainable development and tourism, with special emphasis on health tourism, as one of the specific forms of tourism. In order to substantiate theoretical considerations, as a good practice example, Daruvarske Toplice, the first green health spa in Croatia, is being analyzed. In order to understand the relationship between sustainable development and tourism, both are defined. Sustainable development is a phenomenon from the late 20th century that has begun to be applied in the economy and in all forms of business. Over time, this phenomenon expanded to tourism as tourism itself was one of the main reasons for sustainable development. Over time, such a form was named sustainable development of tourism or professional, sustainable tourism. This means that tourism and all its forms are based on the principles and the concept of sustainable development. According to these principles, health tourism is one of the oldest specific forms of tourism within which professional healing factors are used professionally and controlled, and this is a major indicator of the fact that health tourism operates on the principles of sustainable development. This is how the Daruvarske Toplice operates. They conscientiously and in a controlled manner use natural factors, improve existing infrastructure and build new ones without ruining nature.