Aspergillus ochraceus Wilhelm is a producer of highly toxic mycotoxin, ochratoxin A, and is known to contribute to the damage of grain on storage. Rabbit antibodies were produced against the exoantigens of A. ochraceus, and ELISA and immunoblotting procedures were used to characterize their reactivity towards fungal exoantigens of four Aspergillus, seven Penicillium, three Fusarium, one Mucor and one Alternaria species. The antibodies were specific for A. ochraceus and essentially cross-reacted neither with other fungi nor with the water-soluble grain components. These antibodies, therefore, have the potential of being utilized for the discriminative monitoring of A. ochraceus in foodstuffs and feeds.