An agglutination test by using latex beads (0.8 μm diameter) coated with IgG from the antibodies against extra-cellular polysaccharide of Penicillium digitatum has been developed. As low as 5 to 10 ng/ml of the purified extra-cellular polysaccharide of the same species can be detected by this preparation. Analysis of culture filtrates from 25 different molds showed that the positive reactivity was obtained only with the species of genera Penicillium and Aspergillus . The application of this test was confirmed in testing the samples of spices and nuts. Further, the reliability could be enhanced by including specific blocker in the assay, the synthetic epitopes consisting of four β (1-5)-linked D-galactofuranosyl residues.