PCR-based technology utilizing pairs of primers specific for CBH I and II genes showed that transcripts of cbh1 were detected when Trichoderma pseudokoningii was grown on sophorose and cellulose, but not when grown on glucose, however, cbh2 transcripts were detected in cells under all conditions. These results suggest that CBH I is inducible cellulase and the CBH II is expressed at low constitutive level. Except for transcript of cbh1 from cellulose, all that of cbh1 and 2 were undetected on the above assay conditions, thus implying no low constitutive levels of CBH in Penicillium janthimellum.