An investigation was made into the occurrence and distribution of the enzymes involved in HCN catabolism in different strains of the fungus Trichoderma. Three enzymes, cyanide hydratase, rhodanese and beta-cyanoalanine synthase were studied. All the strains showed a high capacity to degrade cyanide via both the cyanide hydratase and rhodanese pathways. beta-Cyanoalanine synthase, however, was not observed in any of the strains. The enzyme activities were found in varying levels in each of the Trichoderma strains. Experiments conducted with cyanide addition to the medium to assess whether the enzymes were induced in the presence of cyanide failed to show any statistically significant increase. This suggests a constitutive nature of both the enzymes in all the selected strains of Trichoderma used in this study.