The mould latex agglutination test for the determination of immunogenic extracellular polysaccharides (EPS) produced by moulds was compared with the measurement of ergosterol in foods and feedstuffs with respect to sensitivity and applicability to detection of mould contamination. Both assays were able to detect Penicillium aurantiogriseum and Aspergillus niger at the same stage of growth in liquid and on solid substrates. During incubation, ergosterol and EPS content increased parallel to mould colony count and mycelial dry weight. Growth of Fusaria was detected by the ergosterol assay earlier than by the latex agglutination test. Applicability of the two assays was proved by testing 26 naturally contaminated foods and feedstuffs. From all samples positive results with agglutination titres ranging from 100 to 100 000 and ergosterol contents ranging from 0.6 to 56 mg kg‐1were obtained.