The present invention concerns a method for producing recombinant trypsin from porcine pancreas in Pichia pastoris which is soluble and secreted into the culture medium, whereby expression at pH 3.0-4.0 substantially prevents activation of trypsinogen to .beta.-trypsin and autolysis of .beta.-trypsin by .alpha.-trypsin into .epsilon.-trypsin and from there into inactive peptides.