Cultures on autoclaved maize of the phytopathogenic fungus, Drechslera campanulata, were incorporated into diets and fed to male inbred BDIX rats. In a pilot trial, a diet containing 30% D. campanulata culture material killed 5 out of 5 rats in 15-25 days. Lesions included gastric corpus erosions, gastrorrhagia and ulcerative typhlitis. Diets containing 5 % or 10 % culture material induced erosive to ulcerative typhlitis and oedema and hyperplasia of the ileocaecal lymph nodes in 40 out of 40 rats. Other changes included: mass loss; normocytic, hyperchromic anaemia; leukocytosis with neutrophilia; reductions in plasma proteins, creatinine, calcium and cholesterol; elevated serum enzymes; hepatosis, nephrosis and mycoplasma-like interstitial pneumoma. No lesions were present in control rats, and their profiles were normal. Ulcerative typhlitis induced by D. campanulata in rats resembles that seen in chronic piperonyl butoxide intoxication as well as that due to single treatments of indomethacid, although small intestinal ulcers are more frequent in the latter. Overgrowth of intestinal flora may be involved in ulcer pathogenesis. The pathology of drechsleratoxicosis in rats is compared to that in sheep and goats where necrotic lesions in the forestomach and, to a lesser extent, in the caecum are characteristic findings.