Ochratoxin A, one of the most toxic mycotoxins, can be metabolized nearly completely by suspension cultures of various plant cells. The transformation products identified in this study were almost the same in the cell-suspension cultures of maize, carrot, tomato, potato, soybean, wheat and barley, but the quantitative distribution differed strongly depending on incubation time and species of plant-cell culture. The compounds were extracted with ethyl acetate and detected by reversed-phase HPLC with gradient elution. From the result it is supposed that besides ochratoxin A also ochratoxin derivatives may occur in food and feedstuff of plant origin.