A case is described of retrobulbar optic neuritis in a 33-year-old female with acute type B hepatitis. The ocular distress, principally affecting the left eye, followed the normalisation of liver function tests and subsided after steroid therapy. At the onset of ocular symptomatology, complement activation, involving both classic and alternative pathways, and high levels of circulating immune complexes were present. HBsAg was positive. No relapse was observed during follow-up for 3 years. An association between HBV-infection, optic neuritis and an immune complexes-mediated neurotoxic activity are hypothetized.