This paper presents a tar quantification met:hod developed at the University of Stuttgart that allows quasi continuous on-line measurement of the content of condensable hydrocarbons ("tars") in the gas from biomass gasification. The method is based on the comparison of the total hydrocarbon content of the hot gas and that of the gas with all tars removed. Hot gas from the gasifier is led directly into the set up. Hydrocarbons are measured with a flame ionization detector. The method considerably simplifies tar measurements compared to other methods described in literature. A prototype based on the method has been developed and tested. Experiments with the gas from a fluidized bed gasifier and a fixed bed gasifier have been conducted yielding very good results. Tar contents between 200 and 20 000 mg/m(3) have been measured reliably. The experimental procedure is simple and repeatability is good. Sampling and analysis time is two minutes. Continuous on-line monitoring of the tar content in the gas is possible.