Investigations are sometimes required to verify dose assessments or, where the reliability of the original results is known to be in question, to replace them with an estimate of the dose. In Finland, such investigations are conducted by three different parties: the Radiation and Nuclear Safety Authority (STUK), the individual monitoring service (IMS) and the parties operating a radiation practice (the undertakings). The reasons for such investigations as well as the findings from them vary widely between different parties. To determine their usefulness, all investigations carried out on Finnish radiation workers by the STUK, the IMS and the undertakings during 2004-13 have been reviewed. This paper presents the number, reasons for and findings of these investigations. The effect of the investigations on the recorded individual doses as well as on the working methods and other aspects of radiation protection in the work environment are described.