Delayed absorption of subretinal fluid beyond six weeks after surgical repair for rhegmatogenous retinal detachment was recognized in 39 of 575 consecutive cases of scleral buckling. The most common preoperative condition was large clumps of cells on the undersurface of the detached retina (subretinal precipitates). Approximately one in four patients in whom precipitates are seen preoperatively will have fluid persisting beyond six weeks from surgical repair to complete absorption. A second relatively common condition associated with delayed fluid absorption that could be recognized before operation was long-standing peripheral (usually inferior) retinal detachment, which typically spared the macula, was associated with demarcation lines, and was caused by round atrophic holes with or without associated lattice degeneration. An analysis of subretinal fluid protein concentrations in 39 cases showed a positive relationship between protein concentration and duration of detachment. Pigment-laden macrophages in the subretinal space, possibly originating from the retinal epithelium, were common.