In the pyrimidine mol-ecule of the title compound, C(9)H(7)N(3)·C(9)H(6)O(6), the pyridine ring is oriented at 33.26 (11)° with respect to the pyrimidine ring. In the benzene-1,3,5-tricarb-oxy-lic acid mol-ecule, the three carb-oxy groups are twisted by 7.92 (9), 8.68 (10) and 17.07 (10)° relative to the benzene ring. Classical O-H⋯N and O-H⋯O hydrogen bonds and weak C-H⋯O and C-H⋯N hydrogen bonds occur in the crystal structure.