D.c. ERG registrations and EOG recordings were obtained from six patients with vitelliruptive macular degeneration (VMD). In all cases the EOG was highly pathological, but the alpha- and beta-waves of the ERG were normal. This is typical of VMD, which starts as a generalized defect of the pigment epithelium. Four patients showed no evidence of a c-wave. The other patients demonstrated small c-waves, but only under certain stimulus conditions. Thus, varying stimulus durations, intensities and frequencies are sometimes needed to decide whether or not ERG c-waves can be elicited in different diseases or suspected disorders. The findings are in agreement with the presence of a generalized pigment epithelial defect in VMD, since the major positive component of the c-wave is generated by the pigment epithelium-receptor complex.