The working group "Air Analyses" of the German Senate Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area (MAK Commission) developed and verified the presented analytical method. It is used to determine the levels of 4-methyl-3-penten-2-one [141-79-7] that occur in the workplace air. The method covers concentrations in the range from one tenth up to twice the current occupational exposure limit value (OELV) of 8.1 mg/m³. The method is also suitable for verifying the short-term exposure limit (STEL; excursion factor 2). Samples are collected by drawing a defined volume of air through a sampling tube filled with silica gel using a flow regulated pump at a volumetric flow rate of 0.5 l/min. Exposure during the shift is measured with a sampling period of 2 hours and the short-term exposure with a period of 15 minutes. The 4-methyl-3-penten-2-one adsorbed to the silica gel is extracted by liquid extraction with methanol and analysed by high-performance liquid chromatography using diode array detection. The quantitative determination is based on multiple-point calibrations with external standards. A relative limit of quantification (LOQ) of 0.06 mg/m³ is obtained for an air sample volume of 60 litres. As the LOQ for a sample volume of 30 litres is 0.03 mg/m³, the STEL can also be measured. The recovery is approx. 100% and the expanded uncertainty is 14% for a sampling period of 2 hours and below 16% for a period of 15 minutes.