In the article there was made an analysis of recent researches and publications that made the start for resolving the problem of determination of correlation of such definitions as «documenta- tion» and «evidence». Documentation is grounded as the basis for evidence, that is responsible for fixation of factual data in the statements of case. And the latter are used in the evidence within the criminal proceedings. The author made an emphasis on the necessity of legislative consolidation within the act of Ukraine «On Investigative Activities». There was outlined a list of main and additional circumstances that should be documented and proved within the investigative activities and criminal proceedings. In the research there were also defined the main directions of documentation. The necessity to clearly understand the term «evidence» is highly important. Evidence is multi-struc- tured unit of practical, cognitive and logical activity of law empowered subjects. The author made an attempt to define in the article the terms «documentation» and «evidence». The basis for the future scientific researches is grounding of such a term as «undercover investigation» which is a separate form of prejudicial inquiry.

Keywords: documentation, evidence, undercover investigation.