Novel bioactive silica-based organic-inorganic hollow hybrid particles involving Ca2+ ions for stimulating and inducing bone generation were prepared via a teinplatiiig synthesis route. The solid hybrid nanoparticles were first derived from the core-silica particles and natural polymer shell layers that were composed of chitosan and calcium alginate. They were then soaked in a concentrated NaOH solution and subjected to controlled dissolution of the core-silica, which led to yielding the hollow hybrid particles. The resultant particles were spherical in shape. with the porous surface. The polymer shells suppressed the dissolution behavior o f the core-silica. and thus a partially void structure was formed inside the hybrid particles. An Energy Dispersion Spectroscopic analysis indicated that the polymer shells retained much silica and offered a matrix to maintain the spherical shape ofthe partially hollow particles. When soaked in the Kokubo's simulated body fluid (SBF), the hollow particles deposited apatite crystals within one week. that is, they exhibited strong bioactivity. In contrast, it took one month or longer for the apatite to be deposited on the naked silica particles n ithout the polymer shell coatings layers. Thus. Ca in the hollow particles significantly accelerated apatite formation. Therefore, the present organic-inorganic hollow particles could be a promising candidate for bone regeneration drug or factor carriers.