Chitinases, a group of enzymes capable of degrading chitin directly to lower molecular weight products, have been shown to be produced by bacteria, fungi, insects, plants, invertebrates and vertebrates. In previous report, the authors successful cloned and expressed the chi42-SH16 gene encoding 42 kDa chitinase from Trichoderma asperellum SH16 in Saccharomyces cerevisiae INVSc1. In this study, the authors investigated culture conditions for enhancing enzyme expression. The results showed that the highest expression level of 42 kDa chitinase was determined after induction by 4 percent galactose for 12 h of culture at 30°C when cell density (00600) reached a value of 12. For intracellular chitinase extract, the highest activity was found in YPD (yeast extract, peptone and dextrose) medium with total and specific activities were 44.78 u/mL and 85.92 u/mg protein, respectively. For extracellular chitinase excretion, the highest activity was found in YPL (yeast extract, peptone and lactose) medium with total and specific activities were 21.05 u/mL and 41.12 u/mg protein, respectively. Sodium dodecyl sulfate - polyacrylamide gel electrophoresis (SDS - PAGE) of extracellular enzyme from different culture media showed a type of chitinase band with a molecular weight of about 50 kDa (42 kDa of enzyme + 4 kDa of signal peptide + 3.4 kDa of fusion tail of pYES2/NT-C vector). Besides, the intensity of chitinase bands on the gel from different culture media are also consistent with the analysis of enzyme activity.