Tourism is any activity that a person carries out outside the place of residence, regardless of whether it is a business trip or vacation, but not longer than one year. Any person who travels for pleasure, voluntarily and temporarily, is considered a tourist. Tourism appeared in Croatia as early as 150 years ago, and we have been following its development and progress ever since. Tourism is also one of the most profitable branches of the economy in the Republic of Croatia. Along with its numerous tourist destinations, attractions and historical points of interest, Croatia is recognized as one of the most popular vacation destinations. The main objective of the sustainable tourism development strategy is to improve existing services, human resources, and the labor market, to encourage innovation and various forms of tourism. Of course, there are also negative influences in tourism, and one of the most important now is seasonality. The aim of this work is the analysis of tourism as an economic activity in the Republic of Croatia, the analysis of supply, demand and positive and negative impacts on the economy and the environment.