FIELD : chemistry.SUBSTANCE : invention relates to chemistry, biotechnology, medicine and chemical-pharmaceutical industry, and specifically to polyethylene glycol-containing lipid, having a structure of formula 1, where if m=1, then n=18 or n=32–52, and if m=2, then n=20–46. Invention also relates to a composition for delivering extended and short nucleic acids into mammalian cells, which includes polycationic amphiphile 1.26-bis(cholest-5-en-3β-yloxycarbonylamino)-7, 11, 16, 20-tetraazahexacosane tetrahydrochloride for binding and packaging nucleic acids, neutral phospholipid 1, 2-di-O-oleoyl phosphatidylethanolamine for structuring the complexes and said polyethylene glycol-containing lipid, and a method for production thereof. 1.EFFECT : proposed group of inventions provides a wider range of products capable of effectively delivering nucleic acids into tumor cells in vitro in the presence of blood serum in growth medium, as well as in target cells in vivo with intravenous introduction into animal body.4 cl, 3 dwg, 5 ex