Chromatographic analyses and tissue culture toxicity tests were simultaneously carried out with stachybotrys crude toxin. Toxic fractions were localized by tissue culture toxicity tests, and further chemical analyses were concentrated on these parts. By using consecutive partition chromatography on silica gel columns with different solvent systems the crude toxin was resolved into three components which were toxic to mouse primary fibroblast culture. These three toxic stachybotrys components contained some impurities, they were non‐fluorescent and they gave a negative resorcinol tes