Mazdakism was a gnostic religious movement with strong social implications which flourished during the reign of Kavād (a.d. 488-531), caused revolutionary upheavals of a socialistic nature in Iran, but was brutally suppressed at the close of Kavād's reign, mainly through the efforts and machinations of Kavād's son and successor, Khusrau I. A populist and egalitarian movement, it preached in its acute form an equitable distribution of wealth and the breaking or lowering of the barriers which made for the concentration of property and women in the hands of the privileged classes.

The rise of socialism and communism in Europe has spurred special interest in the history of the movement, and Mazdakism has received considerable attention in the past hundred years. The first major attempt at a systematic study of the sect was by T. Nöldeke, who brought together the Greek, Syriac, Arabic and Persian sources, and set forth the essential facts of the history of the movement. His study has served as the basis for all subsequent elaborations; he emphasized the religious nature of the movement, and characterized Kavād as a strong-willed monarch and a capable politician, who leaned towards Mazdakism not so much as an act of faith but as an expedient in order to curb the power of the nobles and the clergy.

E. G. Browne, in his discussion of the 8th and 9th century Persian heresiarchs, drew attention to the affinities between their doctrines and those of Mazdak, and O. G. von Wesendonk in 1919 elaborated on the survival of Mazdakite doctrines among a number of sects, mostly of an Isma'īlī tendency, which sprang up after Abū Muslim's murder, and drew parallels between some Mazdakite doctrines and those of the Druzes of Lebanon.