To examine the amount of rock dissolution accompanying changes in joint permeability, deionized water was forced through axially split cylindrical samples of Vermont marble, subjected to a confining pressure of 60 MPa. Surface preparation and loading conditions varied among experiments during which permeability and fluid chemical composition were monitored with time. Time dependent permeability and fluid composition for freshly polished joints differed from joints which had been ''etched'' by the fluid during previous runs. For freshly polished surfaces, permeability decreased and fluid chemical concentrations increased during the first 50 to 100 hours of fluid flow. For the water-etched surfaces, permeability was not time dependent, and a steady state chemical composition was reached after 20 to 40 hours. A calculation of the steady state chemical concentrations for coexisting calcite and dolomite in deionized water, at a fluid pressure of 10 MPa and a confining pressure of 60 MPa, shows that the steady state values reached in our experiments were supersaturated. Supersaturation was probably due to enhanced solubility at contact points together with precipitation inhibition. Our data indidate that fluid flow through fresh fractures causes dissolution of contact points and permeability reduction, depending on the morphology and state of the fracture surfaces. ¿ American Geophysical Union 1988