A system for the expression of recombinant lumbrokinase (rPI239) was developed in the yeast Pichia pastoris. A total supernatant protein content of 0.174 g/L of high density fermentation broth was obtained. The rP1239 exhibited in vitro fibrinolytic activity. The in vivo activity of rP1239 was measured by prothrombin time, kaolin part thrombin time, thrombin time, and fibrinolytic activity. This work presents the high-density fermentation of rP1239 from P. pastoris and shows that the recombinant protein has similar fibrinolytic activity both in vivo and in vitro. (c) 2006 Published by Elsevier Inc.