Benzoyl peroxide (BPO) was microencapsulated with polyethyl methacrylate (PEMA) by the drying-in-liquid method to apply to a liquid type adhesive. In the experiment, two kinds of calcium carbonate with different shape and size were used as stabilizers. Microencapsulation efficiency over 90% was obtained under the experimental conditions adopted here. Microcapsules prepared were characterized for medical applications. It was found that adhesive biomaterials prepared using microcapsules had sufficient ability for initiating radical polymerization even after two-month storage at 40°C and a relative humidity of 75%. Copyright © 2006 The Society of Chemical Engineers, Japan.