Alginate hydrogel polymer microspheres are usually prepared by inverse suspending method. The main problem is the remained suspending medium and surfactant on the beads. Syringe dropping or extruding method avoids using of the organic solvents. However, it is difficult to control the particle dimension and produce in large quantity. We have developed a new method called nitrogen gas jetting-dropping (GJD) method for the preparation of bovine serum albumin (BSA) imprinted polymer microspheres based on calcium alginate hydrogel. The microspheres can be produced continuously without using any hydrophobic medium or surfactant. The particle diameter is controlled by adjusting pressure and needle dimension. BSA-imprinted alginate microspheres were prepared by the GJD method and the rebinding tests were investigated. The equilibrium rebinding capacity ranged from 0.01 to 0.014 mu mol/g. The imprinting efficiency towards BSA was from 1.46 to 2.17 with the greatest separation factor of 1.523 against a contrastive template ovalbumin (OVA). (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 2331-2339, 2010