The capacity of bee pollen as a substrate for production of ochratoxin A (OTA) by a strain of Aspergillus ochraceus was studied. For control purposes corn, wheat and rice grains, and eleven liquid media were assayed. They were Yeast Extract Sucrose broth (YES), YES supplemented with 0.05, 0.1, 0.5, 1 and 5% bee pollen, YES supplemented with 0.5% peptone, 50% must, Wickerham medium, Aflatoxin Production medium and Coconut Broth Medium. Cultures were maintained at 28 degrees C for 4 weeks and were analyzed every seven days for OTA by liquid chromatography with fluorescence detection. OTA production in bee pollen was significantly (P < 0.01) higher than production in corn, wheat and rice grains regardless of incubation time. With regard to liquid cultures, OTA accumulation in YES supplemented with 5% bee pollen was significantly higher than in pollen-free liquid cultures. A positive correlation between the proportion of pollen added to YES medium and OTA level was observed. This is the first report concerning the use of bee pollen as a substrate to stimulate OTA production. On the basis of the preliminary results obtained in this study it can be hypothesized that bee pollen may constitute an important risk factor concerning the presence of OTA in the diet of consumers of that nutritious food.