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-tetrahydro-7H-purine-2,6-dione (1/1)], C8H10N4O2·C10H7NO4, the components are linked by an O—H⋯N hydrogen-bond and no proton transfer occurs.