Background: Polymeric multilayer capsules are now being engineered to encapsulate various classes of drug molecules, by using polymers that are biodegradable or that can respond and release their payload in response to well-defined stimuli and are produced by stepwise adsorption of oppositely charged polymers onto the surface of colloidal particles followed by core dissolution, which is called Layer by Layer technique, Aim: The present study focuses on synthesis and characterization of polyelectrolyte multilayer microcapsules which was loaded with Bovine Serum Albumin and the cytotoxic effect of the microcapsules on the living cells was studied, Materials and methods: The microcapsules were fabricated by using Poly(allylamine) Hydrochloride (PAH) and Poly(styrenesulfonate) (PSS) as the counter charge polyelectrolytes and biocompatible calcium carbonate as the template which is highly promising to produce capsules for biological applications and loaded with bovine serum albumin (BSA) as a model drug, BSA labeled with fluorescein isothiocyanate (BSA-FITC), Calcium carbonate particles and the microcapsuls were characterized by SEM and TEM ,The effect of microcapsules on Madin Darby Bovine Kidney (MDBK) cell line were studied by using The 3-[4,5-dimethylthiazol-2-y]-2, 5-diphenyltetrazolium bromide MTT assay, Results: CaCO3 microparticles are very convenient template for the preparation of polyelectrolyte microcapsules 1–4μm, preloading method is more effective than post loading method , Our results confirmed that this synthetic CaCO3 microcapsules are cytocompatible, Conclusion: We thus have shown that the very easily prepared, stable, prototypical microcapsules composed of PSS/PAH are useful drug delivery agents for proof-of-principle drug delivery studies.