Osteoporosis is a disease characterized with reduced density and quality of bone. Novel treatment strategies have been developed with the aim to inhibit excessive bone resorption and to increase bone formation. Strontium ranelate (SrRan), a novel orally active agent consisting of two atoms of stable strontium and the organic moiety ranelic acid, has proven drug ability to increase not only the bone mass but also mechanical properties. Despite the advantages it has been shown that systemic administration of SrRan can cause such side effects as diarrhea, hypersensitivity and myocardial infarction. Microencapsulation of SrRan could overcome the possible side effects from the systemic drug use as well as to increase its efficiency by local delivery of drug right to the affected bone site. Thus in the current research an attempt was made to prepare and characterize poly (lactic acid)/srontium ranelate microcapsules and to evaluate the drug interaction with the polymer during the microparticle formation.