Maron’s theory of non-electrolyte solutions has been quite successful for the treat-ment of thermodynamic properties of polymer solutions．However，it has so far been applied to the solutions of polymer in good solvents，where the correct evaluation of eoo is of no importance．It is hereby shown that in order to make the θ-condition deduced from Maron’s cheory to be consistent with the condition A2=O，q should vanish for a polymer in θ-solvent．Consequently a new approximation for the value of eoo is proposed to meet the condition qθ=O，that is，eoo =1-2[n]θ

v instead of eoo=4 used bv Maron and his coworkers．This modification is applied to the treatment of osmotic pressure data of a polydimethylsiloxane fraction in toluene and in butanone at 25℃． If unmodified．the solution in butanone would give a negative value for the second virial coefficient which is evidently unreasonable．