BACKGROUND--Melanoma associated retinopathy (MAR) is a paraneoplastic syndrome in metastatic cutaneous melanoma presenting with nightblindness, light sensations, mild visual loss, and reduced b-waves in the electroretinogram (ERG). METHODS--A patient with MAR was followed for a period of 25 months with repeated examinations including visual field testing and recording of standard electro-oculography, standard ERG, and photopic On and Off responses. RESULTS--A male patient with a very severe course of MAR is described. In addition to the clinical signs seen in previous patients, severe visual deterioration and vitreous inflammation were the predominant signs. The vitreous inflammation resolved after systemic corticosteroid therapy. Nightblindness and the reduced b-waves in the ERG remained unchanged during the follow up period. However, further visual deterioration and paracentral scotomas developed. Dark adaptation was markedly abnormal. Photopic On responses were reduced, but Off responses were preserved. Antibodies against retinal bipolar cells were isolated from blood samples of this patient. CONCLUSION--Vitreous inflammation may mask the diagnosis of MAR. ERG findings indicate that the more severe and progressive course is the result of local retinal changes and not progressive generalised retinal degeneration.