PROBLEMS OF INCREASE OF EFFICIENCY OF PARTICIPANTS OF CRIMINAL TRIAL IN A STAGE OF PRELIMINARY INVESTIGATION Dmitrieva Anna Alexsandrovna, PhD at law, associate professor. <...> Place of employment: South Ural State University (National Research University). <...> E-mael: annadm@bk.ru Annotation: In work the analysis of the available and possible problems of application of measures of the state protection and safety of the participants of process promoting legal proceedings in one stages of modern Russian criminal legal proceedings – in packs of preliminary investigation is submitted. <...> At investigation continuation of security measures which are accepted in a stage of initiation of legal proceedings can take place. <...>