Proteases are important bioactive compounds that have many applications in food processing. In this study, laboratory scale experiments were performed to establish conditions for recovery of a heat stable, acid protease from Pacific whiting (Merluccius productus) surimi process water. Reduction of proteinaceous solids and recovery of protease activity was maximized when process water was pre-treated with acid (pH 4) followed by heat (60 degreesC). In addition, acid plus heat treatment of process water appeared to improve membrane flux and concentration of protease activity (10-fold) was achieved in half as much time as treatments using acidification but not heat, Neither purification nor concentration of protease was effective using either 300 and 1000 kDa ultrafiltration or 0.3 mum microfiltration membranes, However, concentration of protease using 50 kDa ultrafiltration membranes was successful in recovering about 80% of original protease activity. Results provide conditions for further investigations into pilot plant recovery of protease from surimi process water.