The Constitutional and Legal Institute of Religious Freedom in the Penitentiary System is subordinated to and regulated by the rules established by the Federal Executive Body exercising law enforcement functions in the fi eld of execution of sentences (FSIN of Russia). Finding themselves isolated from society, ethnic and practising Muslims, sentenced to imprisonment, feel forced restrictions on the religious freedom. The time and place of Muslims who perform religious rites and rituals are regulated by the documents issued by the Ministry of Justice of Russia were outlined the internal regulations for correctional institutions. The state is entrusted with the duty to provide in prisons a special environment, which would enable the spiritual nourishment of Muslims, whose rights to freedom of religious life are supported by centralized Islamic religious organizations. The civil institutions exercise public control over this implementation. At the same time, the Russian State is increasingly interested in interacting with the main subjects of the religious and penitentiary space. Among them there are offi cial structures of the Islamic Ummah, sending educated imams and Islamic theologians for religious service in prisons, representatives of the Islamic expert community, also there are Public Councils on the problems of the penitentiary system under the Federal Penitentiary Service of Russia. The present author considers the activities of Muslim spiritual departments to provide prison libraries with religious literature (the Holy Quran and semantic translations, the Hadith of Prophet Muhammad, His biography, books on Islamic law) as well as the best examples of religious literature, which manifest the traditional values of Russian Islam and the imperatives of a positive socio-cultural environment to be the signifi cant means of communication in the religious-penitentiary environment.