The article presents the current development trends in private international law. The main focus is on the nature, types and obstacles to unification of private international law norms. Along with unification as a key trend, the article deals with such trends as harmonization, domestication, liberalization, systematization of private international law and extension of the sphere of its application. It has been concluded that current trends of private international law evolution has universal, sustainable and mainly positive nature. Special attention is paid to disputable issues in modern theory of private international law: stages of unification, obstacles to unification, differences between unification and harmonization, adverse effects of the evolution (conflicts of unified norms, variants of international treaties established at different times, different national approaches to international treaties). The trends under analysis are illustrated with cases of supranational and domestic legal regulations of special social relations compounded by international factor.