Agriculture and agricultural extension service are facing numerous problems in present times when good solutions are not easy to find. Providing of agricultural extension service is important foreign-political instrument of a state which has stimulates the development of agricultural production. Agricultural extension service must provide effective link between holdings-producers, agricultural research and other sources of information. Agricultural extension agents must be aware of psycho-social and social aspects of group action and individual counselling. Therefore, one of priorities in agricultural development of our country is rising of the level of extension operation and establishment of extension service based on modern principles. This is the reason why in this paper, some of the traits of the genesis of extension services were indicated, as well as types of extension services and models of the organization, financing and human resources at disposal and structuring of these resources according to main characteristics, for the purpose of modernization and agricultural and rural development.