In the article on the basis of studying of scientific literature and practice the essence and concept of the use of special knowledge have been analyzed. Publications, which made the beginning of this concept research, have being indicated. The author has described the existing in science point of views on understanding of concept of the special knowledge, has pointed out their defects and undertook an attempt to give the determination to this concept. Separate attention in the article is payed to the forms of application of the special knowledge during investigation of crimes. It is determined that to this date the single systematization of forms of application of the special knowledge does not exist. Although in science the validity of selection among the forms of application of the special knowledge such as, judicial and unjudicial, is contested, to the opinion of the author, such systematization deserves on existence.

Keywords: criminal proceeding, proving, special knowledge, forms of application of the special knowledge, judicial expertise.