Exophiala spinifera, one of the etiologic agents of subcutaneous phaeohyphomycosis, may be wrongly identified as Exophiala jeanselmei because of the morphologic similarity of the two species. A reagent containing a precipitin specific for E. spinifera was produced by absorbing antiserum to E. spinifera with E. jeanselmei serotype 1 antigen. Using this absorbed antiserum, we were able to correctly identify isolates of E. spinifera and differentiate them from those of Exophiala alcalophila, E. jeanselmei (serotypes 1, 2 and 3), Exophiala moniliae, Exophiala pisciphila, Exophiala salmonis, Phaeoannellomyces werneckii and Wangiella dermatitidis.