|Trichosporon species are common yeast-like fungi whose primary mode of reproduction is the formation of arthrospores and blastospores. The genus Trichosporon should not be identified by microscopic morphology alone because many related and unrelated fungi form arthrospores. Biochemical analysis is necessary for identification. Trichosporon beigelii (old and common name) is the causal organism of superficial infections of hair shafts (white piedra) and nails (onychomycosis). Other health effects of this genus include reports of endocarditis, meningitis, pneumonia, ocular infections and peritoneal dialysis-associated peritonitis. Disseminated disease is recorded in immunosuppressed hosts. 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, common in soil, fresh and sea water, and plant detritus. Recorded isolations include garden compost, sewage sludge, intertidal sand, running water, and mud.