During a period of 22 months, 9.7% (23 out of 238) of the cattle necropsied at the Department of Veterinary Pathology had mycotic affections in the stomach compartments. The various stomach compartments were affected in the following pattern: omasum: 15 cases, rumen: 10 cases, reticulum: 8 cases and abomasum: 6 cases. In 5 of the animals mycotic affection was also found in other organs of which the liver was most often involved. Out of the 23 cases described, a primary diagnosis of mycosis was only established in 5 cases. In the remaining 18 cases the mycotic infection was regarded as being of a minor importance in the total necropsy result. Macroscopically and histologically the mycotic processes could be grouped into acute, subacute or chronic affections. In 20 cases only one type of inflammation was present, in the remaining cases combinations were found. Identification of the infective agent was performed by immunological staining of hyphal structures in tissue sections. Members of the Zygomycetes were found to predominate as causative fungi. Aspergillus fumigatus was found to have a propensity for infecting the terminal gastric compartments, whereas the Zygomycetes were found regularly in all compartments. Candida spp. were only found in 1 case. Predisposing factors for developing systemic mycosis are discussed. Among these especially the use of antimicrobial drugs, other diseases, metabolic disturbances and stressors in the post parturient period seem to be important.