Some experimental results of the effectiveness of the impregnation of limestone with poly (butyl methacrylate) of low viscosity grade (pbma) and copolymer bmk-5 by means of suction technique are given. The treatment with pbma xylene solutions followed by retarded drying is shown to give a deeper penetration and a more uniform distribution of the polymer in comparison to similar treatment with pbma solutions in mixtures of xylene and ethanol (i: i) and white spirit and xylene (9: i). The treatment with pbma increases the stability of the limestone. Bmk-5 in solvent mixtures penetrates into the limestone at the depth of not more than 3 mm and does not strengthen it.