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 validated the presented biomonitoring method. The analytical method described hereinafter is used to determine the boron concentration in urine using inductively coupled plasma optical emission spectrometry (ICP-OES). The method is rapid, simple, reliable, adequately sensitive and also suitable for routine use in laboratories with high sample throughput. It is possible to determine boron at both occupational and environmental concentrations. Sample preparation is performed by 1/20 (V/V) dilution of urine with 5% nitric acid, which largely reduces matrix interferences.