The title compd. is orthorhombic, space group P212121, with a 4.872(2), b 11.526(4), c 15.811(4) .ANG.; Z = 4, dc = 1.341; T = 110 K; final R = 0.045 for 1713 reflections. At. coordinates are given. Phenanthridine is planar in the solid state with a mean deviation of 0.002 .ANG. from the mean plane of the C and N atoms. The geometries of the benzene fragments in the mol. are rather similar and in the central pyridine moiety the C-N bond lengths are typical of C-N single and double bonds. In the crystal the mols. are stacked according to the screw axes. Comparison with a previous structure detn. of phenanthridine reveals great differences in bond lengths and angles.