Abstract: A method and an apparatus for measuring low energy radiation from a sample provided on a sample carrier (6, 6I). The sample is positioned in a shielded cavity (8) between two oppositely aligned Geiger-Müller tubes (11, 12) such that sample radiation either reaches both of the tubes or one of the tubes, in which case the other tube is for measuring background radiation only. Both tubes are used for measuring coincidental pulses, which are disregarded. A background radiation value, to be subtracted for obtaining a sample radiation value, is determined using either a historical background radiation value or both the historical background radiation value and a background radiation value obtained during the actual sample measurement. In the case of both tubes measuring sample radiation, there can be provided a third Geiger-Müller tube (13) for measuring background radiation only.