Three young ostriches (Struthio camelus), aged 4 months, were found to have zygomycotic proventriculitis and ventriculitis associated with impaction. Clinical signs were anorexia, chronic weight loss, weakness and lethargy followed by scant faeces for seven days. Proventriculi and ventriculi from birds were full of masses of hay, grass, leaves and other fibrous materials in combination with sand, gravel and plastic. Erosions and haemorrhagic ulcers of varying number and severity were present in the mucosae of both organs involved. Mucosal lesions were characterized by haemorrhagic necrosis. Throughout the affected mucosae there were 5 to 12 mu-m wide rarely-septated fungal hyphae with non-parallel walls, irregular branching and occasional globoid distentions, typical of Zygomycetes. Zygomycotic proventriculitis and ventriculitis secondary to impaction was diagnosed.