To summarise the main causes and associations of conjunctival intraepithelial neoplasia (CIN) found in the literature to date.Literature search using Ovid databases on the NHS Scotland E-library, Medline, and the Cochrane Library. The internet search engine Google Scholar was also used to identify relevant articles.The main causes and associations of CIN in the literature are sun exposure and distance from the equator; human papillomavirus infection, increased p53 expression, and HIV seropositivity. It has been found that in HIV positive individuals CIN is on the increase with people being affected with more aggressive tumours at younger ages.Given that CIN is becoming more common in HIV infected populations and that it has the potential to cause severe disability, it is important to improve our understanding of the condition. Early identification of CIN by an understanding of its aetiology and associations may enable the implementation of preventative measures to reduce its incidence and potentially lead to the diagnosis and further management of conditions such as HIV. Young people presenting with CIN in particular may benefit from HIV testing.