The control of synthesis of the cell-wall polymer chitin has been implicated as a crucial event in yeast - hyphal dimorphism of the pathogenic fungus, <i>Candida albicans</i>. This thesis presents evidence that suggests that the activity of the zymogenic enzyme, chitin synthase, is modulated by an endogenous activatory metalloprotease <i>in vitro</i>. The proposed activating protease is characterised and partially purified. A comparison of the intracellular proteolytic activity of yeast and hyphal cells suggest that hyphal cell may be nutrient-stressed compared to yeast cells.