AbstractA soil sample originating from an area of suspected chemical warfare activity was subjected to chemical analysis and bioassay. Sarin and several related compounds were confirmed in the soil by capillary column gas chromatography–mass spectrometry (GC–MS); however, the binding of these compounds to the soil hindered quantitation. The chemical results were then compared to those obtained by bioassay in primary cultures of chick embryo forebrain neurons. By comparing the sample's anticholinesterase activity against those of purified standards in chick embryo neuron cultures, a reasonable agreement was found between the chemical and bioassay semi‐quantitative estimates of sarin content in the soil extract. Furthermore, thein vitrosystem appears to offer a sensitive technique for the estimation of sarin remaining bound to the soil following solvent extraction as well as for an assessment of the potential toxicity of the contaminated soilin