This paper proposes a decision making methodology using clustering methods and fuzzy techniques to determine the optimal location of distributed generation sources into an electrical distribution system. Based on the operational characteristics (loss sensitivity factor and voltage values in nodes) first of all was found the optimal distribution network partitioning, using k-means clustering method and after that were used fuzzy techniques to determine the optimal location of the DG sources for an appropriate DG planning. The suggested method is tested on a 20 kV real rural distribution network with 91 nodes. The results demonstrate that the methodology can be successfully used to determine the optimal DG location into an electrical network without disrupting the proper operation of the entire system.