PURPOSE: To determine the prevalence and factors associated with epiretinal membranes in a random sample of the population aged 40 years and older in Victoria, Australia. DESIGN: Population-based cross-sectional study. METHODS: Detailed eye examinations, including retinal photographs, were conducted in 1992 and 1997 in 3271 people (83% of the eligible) in Melbourne and 1473 (92% of the eligible) in rural Victoria. Eyes present with either cellophane macular reflex (CMR) or preretinal macular fibrosis (PMF) were classified as having epiretinal membranes. Eyes with both CMR and PMF present were classified as having PMF. Age-standardized prevalence rates and 95% confidence limits were calculated by the direct methods using Segi's world population. RESULTS: Epiretinal membranes were observed in 253 of 4313 participants (6.0%; 95% confidence interval [CI] 5.2 to 6.7), bilaterally in 19%. Prevalence increased significantly by age group (0.5% for 40 to 49 years, 2.6% for 50 to 59 years, 9.4% for 60 to 69 years, 15.1% for 70 to 79 years, and 11.3% for 80 years and older). Prevalence was similar in males and females after adjusting for age. The overall age- and gender-standardized prevalence of CMR was 4.8% (95% CI 4.0 to 5.6) and PMF was 1.7% (95% CI 1.2 to 2.3). A decrease in visual acuity (<6/6) was significantly associated with idiopathic PMF (odds ratio [OR] 1.9; 95% CI 1.0 to 3.6) and CMR (OR 1.5; 95% CI 1.1 to 2.0) after adjusting for age. CONCLUSIONS: The prevalence of epiretinal membranes was similar to that reported in other population-based studies. Population shifts in the age distribution to older ages could lead to an increase in mild visual impairment caused by epiretinal membranes.