Hydraulic, electrical, and tracer test results are presented for a natural fracture in granite. The hydraulic and electrical apertures of the fracture are similar and suggest minimal fracture surface-to-surface contact. Tracer aperture exceeds hydraulic aperture indicating transport at a rate less than that predicted on the basis of hydraulic aperture. Numerical simulation of tracer transport reveals that transport within the fracture is not explicable in terms of parallel plate flow and that transport occurs locally at rates in excess of the overall rate defined by tracer aperture. ¿ American Geophysical Union 1993