BACKGROUND: Evidence from animal models and observational studies in humans has suggested that there is an inverse relationship between dietary intake of omega 3 long-chain polyunsaturated fatty acids (LCPUFA) and risk of developing age-related macular degeneration (AMD) or progressing to advanced AMD. OBJECTIVES: To review the evidence that increasing the levels of omega 3 LCPUFA in the diet (either by eating more foods rich in omega 3 or by taking nutritional supplements) prevents AMD or slows the progression of AMD. SEARCH METHODS: We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2012, Issue 4), MEDLINE (January 1950 to April 2012), EMBASE (January 1980 to April 2012), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to April 2012), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 26 April 2012. SELECTION CRITERIA: We planned to include randomised controlled trials (RCTs) where increased dietary intake of omega 3 fatty acids was compared to placebo or no intervention with the aim of preventing the development of AMD, or slowing its progression. DATA COLLECTION AND ANALYSIS: Both authors independently screened titles, abstracts and full-texts of articles to identify studies for inclusion and analysis. MAIN RESULTS: No trials met the selection criteria. The results of a large, multi-centre, randomised trial (AREDS2) that will assess the effects of oral supplementation with omega 3 LCPUFA on progression to advanced AMD are expected in 2013. Two further trials are also ongoing.  AUTHORS' CONCLUSIONS: Until data from RCTs become available for analysis, there is currently no evidence to support increasing levels of omega 3 LCPUFA in the diet for the explicit purpose of preventing or slowing the progression of AMD.