|Geotrichum species are common yeast-like fungi whose primary mode of reproduction is the formation of arthrospores. The genus Geotrichum should not be identified by microscopic morphology alone because many related and unrelated fungi form arthrospores. Biochemical analysis is necessary for identification. Geotrichum candidum is considered part of the normal microbiota of humans. Health effects include reports of endocarditis, encephalitis, and osteomyelitis in immunosuppressed hosts. Pulmonary infections have also been described. Many of these reports lack proper documentation and may be based on unreliable identifications. No information is available regarding toxicity. Allergenicity has not been well studied. Tape lifts and tease mounts from bulk samples may reveal the presence of an arthrospore-forming yeast; isolation on culturable (Andersen) air samples is possible but infrequent. This genus is cosmopolitan, isolated from soil, plants, and many food products, most especially from milk and milk products.