Dedovshchina (Russian: дедовщина, lit. 'reign of old-timers', Russian pronunciation: [dʲɪdɐˈfɕːinə]) is the informal practice of hazing and abuse of junior conscripts historically in the Soviet Armed Forces and today in the Russian Armed Forces, Internal troops, and to a lesser extent FSB, Border Guards, as well as in other armed forces and special services of former Soviet Republics. It consists of brutalization by more senior conscripts, NCOs, and officers. It is a form of non-statutory dominant-status relations between military personnel; the most common form of non-statutory relations, which is a violation of the statutory rules of relations between conscripts, based on the informal hierarchical division of soldiers and sergeants by enlistment and length of service.

The cultural basis of Dedovshchina is made up of traditions, customs and rituals that are passed down from conscript to conscript. Often (but not always), these traditions and rituals are associated with the humiliation of the honor and dignity of servicemen of the later conscription by servicemen of the earlier conscription. Dedovshchina encompasses a variety of subordinating and humiliating activities undertaken by the junior ranks, from doing the chores of the senior ranks, to violent and sometimes deadly physical and psychological abuse, not unlike an extremely vicious form of bullying or torture, including sexual torture and anal rape. There have been occasions where soldiers have been seriously injured or killed.

The term is derived from "ded" (Russian: дед, lit. 'grandfather'), which is the Russian Army slang equivalent of gramps, meaning soldiers after their third (or fourth, which is also known as dembel (Russian: дембель or "DMB" Russian: ДМБ)) half-year of compulsory service, stemming from a vulgarization of the word "demobilization" (Russian: демобилизация, romanized: demobilizatsiya – this word is erroneously used by soldiers to describe the act of resigning from the army); soldiers also refer to dembel half-year of conscription, with the suffix -shchina which denotes a type of order, rule, or regime (compare Yezhovshchina, Zhdanovshchina). Thus, it can literally be translated as "rule of the grandfathers". This is essentially a folk system of seniority based on stage of service, mostly not backed by code or law, which only grants seniority to conscripts promoted to various sergeant and yefreitor ranks.

Non-statutory relations are a broader concept than dedovshchina. Non-statutory relations include the entire range of relationships between servicemen that are not described in the general military regulations (including the relationship between a superior and a subordinate, a subordinate and a superior). Dedovshchina in its narrowest sense covers only those violations of regulations that are related to the relationship between senior and junior enlisted personnel.

In addition, the modern science of criminal and administrative law distinguishes between crimes committed within the framework of the so-called dedovshchina and "barracks hooliganism". The distinguishing feature here is the subjective side of the offense. In the first case, the intention of the offender is aimed at asserting his status as an old soldier, forcing a young soldier to perform household chores, performing certain rituals related to the "dedovshchina traditions", etc. In the second case, the offender's unlawful actions are motivated by personal hostile relations, national, ethnic, religious hostility, property relations, unexpectedly arising hostile relations, etc.

Thus, violations of the statutory rules of relations between servicemen that do not involve relations of subordination within the framework of dedovshchina can be qualified as an encroachment by senior servicemen on the rights, honor, dignity, and personal integrity of junior servicemen.

Often, the phenomenon of dedovshchina is directly related to the ratio of physical and moral strength of the "grandfathers, granpas, veterans, old men, dembels" (slang for "masters") and "devils, spirits, dushar, chekists, cheka, salabons, thingmen, young, elephants" (slang for "slaves").

One of the major negative effects of dedovshchina as a phenomenon is that this army subculture seriously undermines the authority of the army among young people of conscription age and is one of the main reasons for evading military service.