The thermal behaviour of thermoreversible gels prepared well below room temperature from isotactic poly(methyl methacrylate) (i-PMMA) in butyl acetate (BAG) was investigated by means of differential scanning calorimetry. Gel-formation and gel-melting enthalpies together with melting enthalpy of the solvent were determined as functions of polymer concentration. The results are consistent with the existence of a polymer/solvent complex with a stoichiometry of 1,5-2 BAC molecules per i-PMMA monomeric unit.