Keratoconus sufferers form a significant proportion of patients for a practitioner specialising in corneal diseases. Yet it is a disease where the pathogenesis is poorly understood and until recently there has been no treatment apart from transplantation that could be offered which was curative or even capable of slowing the progression of the disease. Collagen cross-linking treatment using riboflavin and UV light has been developed to address this need and the initial results are promising. The purpose of this review is to critically evaluate this treatment in the light of the scientific basis for cross-linking; to highlight the strengths and limitations of the evidence in terms of efficacy and long-term safety and finally to identify areas for future research in this exciting area with a significant potential to change the way we treat our keratoconus patients. In addition, we hope that our unbiased review for the first time would bring together, in a concise fashion, scientific information for a practitioner contemplating on offering this treatment and to help inform their patients of its potential risks and benefits.