Abstract: A cloned gene (epr) encoding a novel extracellular protease, Epr, from Bacillus subtilis is described. Also described is a triple extracellular neutral, alkaline and serine protease deficient Bacillus subtilis mutant strain having deletions in the (npr), (apr) and (epr) genes encoding these proteases. The triple mutant strain was constructed by the gene conversion technique and produces about 1% of the extracellular proteolytic activity of the wild type. It is a particularly useful host for the production of heterologous proteins that are secreted into the growth medium.