The working group “Analyses in Biological Materials” of the Permanent Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area developed and verified the presented biomonitoring method. Selenium is used in different industrial processes. In the workplace, employees are mainly exposed to elementary selenium and inorganic selenium compounds. In contrast, the non-occupationally exposed general population ingests mainly organic selenium compounds, like selenomethionine and selenocysteine, via the diet. Following exposure, selenium can be determined in serum/plasma and in whole blood/erythrocytes. While the selenium concentrations in these matrices reflect exposure from recent weeks or even months, urinary selenium concentrations are suitable for the determination of short-term exposure (e.g. of the last shift). The aim of this work was to develop a selective method for the determination of total selenium in urine while avoiding the selenium enhancement effect caused by volatile selenium species (e.g. dimethyl selenide or dimethyl diselenide). The method has been comprehensively verified, and the reliability data have been confirmed by replication and verification of the procedure in a second, independent laboratory. Urine samples are mineralised by microwave-assisted digestion using an acidic hydrogen peroxide-containing solution, thereby converting the various selenium species present in the urine into selenite. The selenium concentrations in the diluted digestion solutions are determined by mass spectrometry with inductively coupled plasma (ICP-MS) on m/z = 78. Germanium is used as internal standard. The microwave-assisted digestion allows for the accurate quantification of total selenium in urine even when volatile selenium species are present in the samples.