In comparison with several other filamentous fungi, such as Aspergillus nidulans and Neurospora crassa, our understanding of the genetics of species of Acremonium is still in its infancy. Much of the work that has been done has centered on Acremonium strictum (Cephalosporium acremonium), which is not surprising in view of its commercial importance. (For the purposes of uniformity in this text the revised name A. strictum will be used; however, it is recognized by the author that the fungus is still generally known, especially in industrial circles, as C. acremonium and that it is most likely that this situation will continue.) More restricted studies have been carried out on Cephalosporium mycophilum (Tuveson and Coy, 1961) and on a representative perfect stage of Acremonium, Emericellopsis salmonsynnemata (Fantini, 1962).