FIELD: medicine, pharmacy, peptides. SUBSTANCE: invention relates to method for preparing biologically decomposable polymeric microspheres or nanospheres using method "oil-in-water". Microspheres or nanospheres can be used for sustained-release of biologically active peptides. For reduced solubility in water medicinal peptide is used as free base adsorbed on biologically decomposable inorganic matrix, such as hydroxyapatite or monosubstituted calcium phosphate, or as salt insoluble in water but soluble in organic solvent. Invention provides high effectiveness of incapsulation of water-soluble peptide that exceeds 85%. EFFECT: enhanced effectiveness of method. 48 cl, 2 tbl
