In following a formerly successful protocol designed to produce antibodies to A. fumigatus (Fres) we observed a disseminated, lethal fungal infection in healthy, specific pathogen-free (SPF) rabbits. The pathomorphological findings included multiple miliary to avenaceous whitish nodules in the livers and kidneys, mycotic mesencephalitis, nephritis, hepatitis, myocarditis, hemorrhagic enteritis, and splenitis. The hyphae were surrounded by necrosis, which also occurred in the liver without the hyphae. Comparative gas chromatographic and metabolic investigations on this strain and some environmental A. fumigatus strains showed significant differences. The findings are discussed with particular reference to the pathogenicity of A. fumigatus.