Enzyme-catalyzed synthesis of a phenolic polymer within layer-by-layer (LbL) constructed polyelectrolyte microcapsules has been introduced. This approach is based on selective permeability of capsule walls for monomer molecules, while biocatalyst and forming polymeric chains cannot leave capsules interior because of high molecular weight. Horseradish peroxidase was encapsulated into four bilayer poly(styrenesulfonate)/poly(allylamine hydrochloride) capsules with an average diameter of 5 pm using pH-driven pore opening. 4-(2-Aminoethyl)phenol hydrochloride (tyramine) was used as a monomer giving easily detectable fluorescent polymeric products after addition of hydrogen peroxide into the system. Filling of the capsules with polymer was confirmed by different methods (AFM, quartz crystal microbalance, and confocal microscopy).