BACKGROUND: The aim of the current study was to identify a possible locus of dysfunction in the visual system of depressed patients. MATERIALS AND METHODS: Fifty Major Depressive patients aged 21-60 years and 15 age-matched controls took part in the study The diagnosis was obtained with the SCAN v 2.0. The psychometric assessment included the HDRS, the HAS, the Newcastle Scales, the Diagnostic Melancholia Scale and the GAF scale. Flash Electroretinogram and Electrooculogram were performed in all subjects. The statistical analysis included ANCOVA, Student's t-test and Pearson Product Moment Correlation Coefficient were used. RESULTS: The Electro-oculographic findings suggested that all subtypes of depressed patients had lower dark trough and light peak values in comparison to controls (p < 0.001), while Arden ratios were within normal range. Electroretinographic recordings did not reveal any differences between patients and controls or between subtypes of depression. DISCUSSION: The findings of the current study provide empirical data in order to assist in the understanding of the international literature and to explain the mechanism of action of therapies like sleep deprivation and light therapy.