The scientific article is devoted to the determination of the content and legal nature of the concept of "reasonable terms" in national judicial proceedings. It has been established that a reasonable period of trial is a separate element of access to justice, which is not limited to the speed of making a decision or resolving a dispute in a case, its author's definition is formulated. Based on the research of scientific concepts in this field, a review of judicial practice and the practice of the European Court of Human Rights, the criteria of reasonableness of time limits during the implementation of legal proceedings (complexity of proceedings, behavior of its participants, organization and procedure of legal proceedings, significance of proceedings for interested parties) were determined. It was concluded that the observance of the selected criteria in the national judiciary, taking into account the individual approach to determining the duration of the relevant procedures, will lead to greater efficiency in the consideration of criminal, civil and administrative cases.