A numerical study of a single fracture embedded in a porous matrix was performed to investigate the role of fracture coatings and fills on water movement in permeable, fractured porous media. The variables considered were conductivity and continuity of fracture coatings; location, length, and conductivity of fracture fills; combinations of fills and coatings; initial matrix saturation; and inflow boundary conditions. Results from the simulations indicate that in low-saturation, high-capillarity tuff systems, the conditions under which fractures act as rapid flow paths are limited. These conditions include a continuous coating with conductivity several orders of magnitude lower than that of the neighboring matrix, and large inflow rates. However, as initial matrix saturation increases, the amount of fracture flow also increases. Discontinuities in coatings substantially reduce their effectiveness in preventing matrix imbibition. The presence of any coating, however, does produce increased infiltration depths. Fills appear to be effective barriers to fracture flow. ¿ 1998 American Geophysical Union