Billy's mortar , a Swedish product based on lime-cement and ground sandstone with acrylate dispersion, is employed by conservators for the repair of Gotland sandstone monuments. Experiments were carried out at the Institute of conservation and restoration of historic monuments of Nicholas Copernicus University, in Torun (Poland), to assess its physical and mechanical properties and suitability for conservation purposes. The paper gives a detailed discussion of test results, pointing out the advantages of Billy's Mortar in stone repair. 1 bibliographic reference. Diagram. Data table.