Until 1990 the Ministry of Internal Affairs operated the penal system through its Central Prison Institutions Department and its Prison Service. The latter organization trained and administered prison guards. In 1990 the system included thirteen prisons and twenty-six minimum-security facilities housing 6,600 prisoners. Major prisons were located in Bobov Dol, Pazardzhik, Plovdiv, Sofia, Stara Zagora, Varna, and Vratsa. In 1990 authorities reported that the total prison population had declined by 10,000 as a result of amnesties granted to political prisoners during the previous three years. The remaining prison population included a high percentage of repeat offenders and prisoners convicted of serious crimes. The institution at Pazardzhik reported more than 560 inmates, including more than 50 imprisoned for murder, 60 for rape, 140 for other crimes against persons, and the balance for crimes against property. Offenders guilty of less serious crimes served time in minimum-security facilities including open and semiopen labor camps. Prison strikes and demonstrations began with the Zhivkov ouster, continuing and escalating through the first half of 1990. Sparked by the release of large numbers of political prisoners, massive strikes elsewhere, and the suddenly volatile sociopolitical climate, the strikes became violent, and several inmates reportedly immolated themselves to protest prison conditions. Red Berets were called upon to reinforce Prison Service guards. By 1991 Bulgaria had already implemented one stage of prison reform to improve its international human rights image: prisons were put under the Ministry of Justice instead of the Ministry of Internal Security.

Data as of June 1992