Paraneoplastic retinopathy is a cancer-related non-metastatic retinopathy mainly associated with lung cancer. We examined two patients with presumed paraneoplastic retinopathy, both ophthalmologically and electrophysiologically. Both patients presented with initial visual complaints of moderate reduction of visual acuity. No specific fundus anomaly was found in the fundus except for a mild attenuation of the retinal arteries. The electroretinogram and pattern reversal visual evoked responses were either markedly reduced in amplitude or non-recordable. The electrooculogram recorded in one patient demonstrated a markedly reduced light peak/dark trough ratio. These results indicate the presence of a severe and diffuse bilateral retinal dysfunction, despite the relatively good visual acuities and mild fundus changes. Electrophysiological evaluations play an important role in the diagnosis of paraneoplastic retinopathy.