Six cases of congenital pit of the optic nervehead associated with posterior serous retinal detachment are presented. All were treated by photocoagulation along the disc margin in the area of retinal detachment. In five cases reattachment of the retina occurred, after the clinical development of a film chorioretinal adhesion at the disc margin, and appeared to be secondary to the treatment. The sixth case (Case 4), although treated, appeared to represent a spontaneous reattachment. This disorder, which frequently results in permanent decrease of central vision, affected the better, or only, eye in two of the six cases herein reported. Fluid, probably from the vitreous cavity, appears to gain access to the subretinal space via the pit. Reattachment in treated cases occurred only if an effective chorioretinal adhesion was created over the entire area of the fistulous detachment at the disc margin. Field defects after treatment appear to be secondary to either the optic pit itself or the longstanding retinal detachment, oftern accompanied by pigmentary degeneration and cystic macular degeneration, rather than juxtapapillary photocoagulation treatment.