The growth factor bone morphogenetic protein 2 (BMP-2) is utilized in surgical procedures to improve bone regeneration; however, current treatments deliver BMP-2 at amounts greater than 100 000 fold of physiological levels, which increases treatment costs and risk of side effects. Drug-eluting microcarriers developed to improve these therapies have faced significant commercialization challenges including particle size distributions, solvent removal, low encapsulation efficiency, and bioactivity loss. In this study, a solvent-free method is presented for fabrication of uniform polyHIPE microspheres for controlled growth factor release. Emulsion templating principles and fluid dynamics were used to fabricate uniform particles with tunable particle size (200-800 mu m) and pore size (10-30 mu m). The ability to independently tune particle and pore size is expected to provide excellent control of release kinetics. Overall, this solvent-free method for making porous microspheres displays strong promise for the controlled release of BMP-2 and other growth factors.