A gene encoding endochitinase activity was isolated by PCR from Saccharomyces cerevisiae NCYC686 and placed under the control of fungal transcriptional elements regulating glucoamylase expression. Following transformation of Aspergillus awamori with this expression construct, heterologous endochitinase was induced in positive transformants by the addition of starch to the growth medium. A series of optimisation and process development studies were then undertaken, the result of which was the production of heterologous endochitinase activity at 343 U g(-1) of total protein. It was found also that the yield of enzyme decreased upon scale-up from shake flask to 3 l pilot scale.