This dissertation presents results and conclusions of the research of small hydroelectric plants from different aspects. The research of the existing planning methodologies in the electric power supply system have been conducted, with the emphasis on the defining of real locations of small hydroelectric plants, i.e. with the emphasis on their impact on decision-making by using planning methods which are nowadays used in our country on various levels of the system. This aspect has also been analysed from the legislature point of view, bearing in mind the opening of electric power market and the specific privileged position of renewable energy sources in the electric power system. Moreover, the spatial-planning aspect has also been taken into consideration as a second most important aspect when it comes to the objects whose construction is very delicate from the point of view of environment and heritage protection. On the one hand, the research of the regulations has been done, and on the other the field research of the particular projects of small hydroelectric plants, and some conclusions have been made concerning the acceptability, i.e. the possibility of implementation of particular projects. In doing so, it has applied the individual approach for every potential location suitable for the construction of small hydroelectric plant, which presents the novelty in the up till now experience. Besides, a special attention has been paid to technical aspect in the narrow meaning of the word, i.e. to technical and technological characteristics of small hydroelectric plants. Research of the plants in operation has also been done together with the comprehensive variant analysis, and all this led to the real state of being when it comes to location and the importance of small hydroelectric plants in the electric power system. Finally, the estimate of the contribution of the construction of small hydroelectric plants for the society has been done, and, taking into account all the conclusions from the previously mentioned research and analysis, a new approach to construction plans for small hydroelectric plants in our country is suggested. This project has united all the important aspects of the small hydroelectric plants in a completely new way, and as such it presents the first attempt of uniform, multidimensional approach to construction of small hydroelectric plants in Croatia, with the special emphasis on the impact of small hydroelectric plants on the environment in the broadest sense of the word.