Aim — to assess the relationship between structural abnormalities of the junction of the internal and external segments of photoreceptors (IS/OS junction) and functional changes. Material and methods. The study enrolled 45 patients (90 eyes) with Stargardt disease, of them 22 women and 23 men. Ophthalmic examination included color vision test, static perimetry with a 60° field of view, electrophysiological studies, namely, ganzfeld and multifocal electroretinography (gERG and mfERG), autofluorescence, and optical coherence tomography (OCT). Results. For analysis, the patients were divided into 3 groups depending on whether or not the structure of the IS/OS junction was damaged at OCT. A strong correlation has been found between the level of IS/OS damage and the MD index. There were no differences in foveal, perifoveal, or parafoveal retinal thicknesses. Retinal volumes within the 1-, 3- and 6-mm ring-shaped zones were also similar. All three groups showed a reduction in amplitudes of the major gERG waves and mfERG changes of different severity. The most frequent defect seen in all groups and the ring-shaped zones was a reduction in the amplitude and density of retinal biopotential (P1μv and P1 nv/deg2). Conclusion. A direct correlation exists between the extent and severity of structural changes in the IS/OS junction at OCT, visual functions assessed with perimetry, and disturbance of electrogenesis detected by mfERG and gERG.