A molecularly imprinted nanocapsule was prepared, which showed excellent site accessibility and potential in delivery applications. The monomer-template complex (Est-Vinyl) was synthesized by the reaction of 3-isopropenyl-alpha,alpha-dimethylbenzyl isocyanate with estrone, where the template was linked to a polymerizable vinyl group via a thermally reversible urethane bond. Microemulsion polymerization of Est-Vinyl, styrene, and divinylbenzene was carried out in water and octanol by using potassium persulfate as an initiator to produce a nanocapsule having a cross-linked polymeric wall. The hollow structure of the nanocapsule was confirmed by transmission electron microscopy. The template was removed from the polymeric wall by means of a simple thermal reaction. In aqueous media, the imprinted nanocapsule solubilized hydrophobic pyrene. When the imprinted nanocapsules were previously incubated in a template (estrone) solution, pyrene Could not transfer effectively into the interior of the nanocapsules, suggesting that the imprinted sites were blocked by the template molecules.