Three dimensional nanofiber materials made of poly-L-lactic acid (PLLA) and produced by electrospinning are commonly used in regenerative medicine and as a base for drug delivery systems. Surface modification of such materials allows manipulating their chemical, physical, and biological properties. Previously, our group reported a number of modification strategies for thin PLLA films, based on the "solvent/non-solvent" technique. Most biologically active agents may not be adsorbed on the surface of PLLA. Proposed treatment allows partially dissolving the polymer surface in order to adsorb biologically active molecules or linkers. The aim of this work was to investigate the influence of solvent/nonsolvent mixture composition on the morphology and crystal structure of the electrospun PLLA scaffolds and to select the solvent system for further scaffolds modification in order to impart them biological activity. PLLA scaffolds were treated with mixtures of toluene and ethanol in different compositions. By means of scanning electron microscopy, it was shown that solvent/non-solvent treatment had no critical effect on the morphology of the scaffolds. The results of X-ray diffraction analysis revealed that treatment of the scaffolds with investigated solvent systems did not lead to the formation of the additional phases and the size of the polymer crystallites as well. Thus, selected solvent system will be used for modification of the PLLA electrospun nanofiber material for biomedical application.