This paper reports the preparation of CaCO3 microcapsules and the direct encapsulation of biomacromolecules such as bovine serum albumin (BSA) and duplex DNA into the CaCO3 microcapsules. Vacant CaCO3 microcapsules were effectively obtained by interfacial reaction method using carbonate salts and calcium salts, which were dissolved in inner water phase or outer one, respectively. For the fabrication of microcapsule structure, the formation of vaterite as a metastable phase of calcium carbonate crystal was an important factor. When some biomacromolecules were dissolved in the aqueous solution of (NH4)(2)CO3 as the inner water phase, these macromolecules were successfully encapsulated into CaCO3 microcapsules. Biomacromolecules included in the microcapsules scarcely eliminated without the fracture of the microcapsule particles. These properties of encapsulated biomacromolecules might be utilized in various bio-related materials. (C) 2007 Elsevier B.V. All rights reserved.