IN THE CRYSTAL STRUCTURE OF THE TITLE ADDUCT [SYSTEMATIC NAME: 2-(1,3-dioxoisoindolin-2-yl)acetic acid-1,3,7-trimethyl-1,2,3,6-tetra-hydro-7H-purine-2,6-dione (1/1)], C(8)H(10)N(4)O(2)·C(10)H(7)NO(4), the components are linked by an O-H⋯N hydrogen-bond and no proton transfer occurs.