The incidence of nephrotoxigenic Penicillium species on farm-stored cereals in western Canada was determined by morphological and metabolite profile examination. Of the 142 isolates examined 102 were toxin producers with 61 P. aurantiogriseum and 27 P. freii. Other nephrotoxigenic species included P. tricolor (6 isolates), P. verrucosum Chemotype II (4 isolates) and P. viridicatum Westling (4 isolates). The nephrotoxigenic Penicillium species profile for western Canada appears to differ from that of Denmark where P. verrucosum, P. cyclopium, P. freii and, to a lesser extent, P. aurantiogriseum, P. polonicum, and P. viridicatum predominate.