The structure of ortho-vanillin, C(8)H(8)O(3), has been revisited with modern methods and at low temperature (100 K). The previous structure [Iwasaki et al. (1976 ▶). Acta Cryst. B32, 1264-1266] is confirmed, but geometric precision is improved by an order of magnitude. The C atom of the meth-oxy group lies close to the benzene ring plane, which is the most common geometry for -OMe groups lying ortho to -OH groups on an aromatic ring. The crystal structure displays one intra-molecular O-H⋯O and three weak inter-molecular C-H⋯O hydrogen bonds.