Visual loss is not uncommon and many patients end up seeing neurologists because of it. There is a long list of possible causes but in most patients visual loss is associated with visual field loss. This means that for practical purposes the differential diagnosis can usually be narrowed down to a manageable shortlist by consideration of where in the visual pathway the lesion is likely to be, along with the time course of the visual loss. This article provides a practical approach to the diagnosis and appropriate investigation of such patients, dividing them into four groups: those in whom vision is lost transiently, acutely, subacutely (i.e., days to weeks) and over a longer time frame (months to years). In addition, there is a discussion of those patients in whom visual loss is not obviously accompanied by any visual field loss.