A review of the available evidence for the associations between environmental sanitation and transmission of trachoma was undertaken with a view to identifying preventive interventions. The WHO Global Alliance for the Elimination of Trachoma by the Year 2020 (GET2020) has adopted the "SAFE" strategy, consisting of four components: Surgery, Antibiotic treatment, promotion of Facial cleanliness and initiation of Environmental changes. This review of 19 studies selected from the 39 conducted in different parts of the world shows that there is clear evidence to support the recommendation of facial cleanliness and environmental improvements (i.e. the F and E components of the SAFE strategy) to prevent trachoma. Person-to-person contact and flies appear to constitute the major transmission pathways. Improvement of personal and community hygiene has great potential for a sustainable reduction in trachoma transmission. Controlled clinical trials are needed to estimate the relative contribution of various elements to the risk of transmission of trachoma and the effectiveness of different interventions. These could show the relative attributable risks and effectiveness of interventions to achieve improvement of personal hygiene and fly control by environmental improvements, alone or in combination, and with or without antibiotic treatment.