At least 673 congressmen from 44 nations countries suffered death or other threats, most of them in countries ravaged by political strife and instability.
IPU published these annual figures on the eve of Human Rights Day, which will be celebrated on December 10.
The data has confirmed a steady increase in the number of cases reported by the IPU Committee on the Human Rights of Parliamentarians.
This Committee is made up of international lawmakers and responds to complaints of abuse suffered by their colleagues.
According to IPU, political figures face abuse, mistreatment or even death, and the IPU Committee´s role is to try to protect and defend them.
The 2021 figures account for a 22% increase over previous year, in which 552 deputies from 42 countries said they were harshly persecuted.
Most of the cases concerned opposition deputies from Brazil, Libya, Pakistan and 13 other countries, who were abused directed by government forces.
The most common violations reported were the undue suspension and revocation of the parliamentary mandate, censorship, threats, acts of intimidation and lack of a fair trial, the statement said.