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Sixty-seven European isolates of Heterobasidion annosum belonging to intersterility groups S, P and F were cultivated on agar plates and their fatty acids and sterols were extracted and analysed. Fifteen fatty acids, five sterols, one naphthalenone and two unidentified extractives were detected in glc. The amount of octadecanoic acid in 13 of the strains decreased considerably during successive cultivations and contents of this fatty acid were not used for statistical calculations. Multivariate discriminant analysis revealed distinct differences between contents of fatty acids and sterols (= FAST-profiles) of the three intersterility groups but not between geographical origins of the strains. Type S strains generally contained more hydroxy fatty acids and sterols than type P strains and type F strains were characterized by a high total amount of extractives. Group F, according to averaged FAST-profiles, is more closely related to S than P. Several ‘outlier’ strains having exceptional FAST-profiles were found in all three intersterility groups. Only a small part of the FAST-profile diversity of the investigated strains could be explained by intersterility group or geographical origin: FAST-profile mismatch values between all strains were on average only slightly higher (16·4) than those within intersterility groups of various geographical origin (14·9).