The crystal structure of Na5Ba3N was determined from a single crystal grown by a diffusion limited process (Pnma, a = 11.882(2) Angstrom, b = 7.049(1) Angstrom, c = 17.792(4) Angstrom, Z = 4, R = 0.063). The structure contains Ba3N chains nearly identical with those found in NaBa3N. The structure can be explained in terms of strong Ba-N intrachain ionic bonding and weak Ba-Na metallic bonding separating the chains. Na3Ba3N is a common impurity phase in Na-Ba alloys, which has probably exacerbated the difficulties in determining Na-Ba phase equilibria. Na5Ba3N has the structural characteristics of a one-dimensional void metal.