Purpose: To perform an electrophysiological study of central areolar choroidal dystrophy (CACD) in the affected members of a four generation family. Methods: Eight affected family members from the last three generations of a family affected by CACD were assessed by full-field electroretinograms (rod response, maximal combined response, oscillatory potentials, single-flash cone response and 30Hz flicker responses) and electro-oculograms. In addition three members of the youngest generation, who were visually asymptomatic, had pattern visual evoked potentials (PVEPs) and pattern electroretinograms (PERGs) performed. Affected status had been determined previously by genetic analysis. Results: Three youngest generation family members, who were considered affected by genetic haplotype analysis, had no visible optic nerve or retinal abnormalities. All of these subjects had abnormal PVEPs and PERGs in both eyes. Abnormalities were also detected in two of these subject's Rod ERGs, Cone ERGs and one of these subject's Maximal ERGs and 30Hz ERGs. Electrophysiological examination in the older generations demonstrated a similar, more advanced, cone and rod dysfunction. Conclusions: All affected, but clinically normal, youngest generation patients had bilaterally abnormal PVEPs and PERGs. In CACD the PVEP and PERG proved to be the most sensitive electrophysiological tests of preclincial macular dysfunction, 3/3 subjects abnormal. ERG recording to ISCEV guidelines were very useful in these cases; 7/8 subjects abnormal. The EOG was less useful; 4/8 subjects abnormal. CACD produces a widespread photoreceptor dysfunction in its later stages.