The pathophysiology of central serous chorioretinopathy is incompletely understood but appears to involve the retinal pigment epithelium. We recorded consecutively the fast oscillation, hyperosmolarity response, acetazolamide response, and light peak from four patients with active central serous chorioretinopathy and three normal subjects to determine whether the affected eyes showed any electrophysical abnormalities. We found essentially no differences in any of the four responses between the active and the inactive eyes of the patients or between patients and normal subjects. Whatever retinal pigment epithelial dysfunction exists in central serous chorioretinopathy is unassociated with clinically evident changes in these retinal pigment epithelial electrophysiologic responses.