Laboratory studies on fluid flow in single fractures in rock samples up to a meter in size suggest that there is a definite problem of scale. Two such studies have been reported, but the results are not consistent. The seemingly contradictory results may simply be a manifestation of the effects of fracture surface roughness. A basic problem in attempting to understand the physics of fluid flow in fractures is that of understanding the effects of surface roughness. The investigations that are envisioned to attack this problem will only be possible on rock samples that are much larger than the conventional size.