Abstract
Two relatively new opportunistic diseases — hyalohyphomycosis and phaeohyphomycosis — are the byproduct, in most cases, of the progress being made in combating microbial and non-microbial diseases. Immunologically impaired hosts have become vulnerable to infection by fungi that were long considered to be innocuous. The currently known etiologic agents of these two diseases are listed and pertinent literature references are cited. The basic histologic differences between phaeohyphomycosis and chromoblastomycosis was emphasized and illustrated.