Background: Central register of data on exposure to carcinogenic or mutagenic chemical substances, their mixtures, agents or technological processes (CRCR) conducted by Nofer Institute of Occupational Medicine (NIOM) enables monitoring of such agents occurrence in working environment in Poland. The NIOM conducts CRCR based on the provisions of the Regulation of the Minister of Health of 24 July 2012 on chemical substances, their mixtures, agents or technological processes with carcinogenic or mutagenic effects in the work environment. The work summarizes the information reported to CRCR in 2018–2021. Material and Methods: The data were extracted from CRCR, to which it was transferred by sanitary inspections. The data were extracted from CRCR. Data in this register is gathered based on employers’ notifications to sanitary inspection. The study includes the number of reported agents (chemical substances and technological processes), the number of enterprises and the number of persons exposed to particular groups of agents (chemical substances, technological processes, ionizing radiation). Results: The number of substances notified to the CRCR increases, from 382 reported substances in 2018 to 444 in 2021. Significant increase in the number of enterprises reporting technological processes (from 981 in 2018 to 5422 in 2021) and the number of exposed persons results from the law amendments extending the list of carcinogenic or mutagenic processes. Conclusions: The CRCR is a unique database on the occurrence and exposure to occupational carcinogens and mutagens, in which data from over 20 years has been collected. The increase in the number of reports to the register was mainly influenced by legislative changes regarding carcinogenic or mutagenic agents. Due to amount and complexity of data, they can be used for analysis in projects and programs aimed at raising awareness and reducing risk of occupational exposure to carcinogens and also during legislative works in Poland and in the EU. Med Pr Work Health Saf. 2023;74(5):399–407.