The optic neuritis of systemic lupus erythematosus (S.L.E.) more frequently results in the persistence of a central scotoma or complete blindness after a single attack than demyelinating optic neuritis, although the initial clinical presentations may be identical. A significant number of patients, however, recover normal vision. Optic neuritis may be the presenting symptom of S.L.E. and as myelopathy may also occur in the course of the disease, confusion with multiple sclerosis may result, especially if there are no arthritic, cutaneous nor visceral manifestations. We report a case of lupus optic neuritis associated with anticardiolipin antibodies and a circulating lupus anticoagulant and suggest these may be a marker for vasculitic optic neuritis and play a role in its aetiology.