To report population data on the association between homocysteinemia and retinal vein occlusion (RVO). Cross-sectional, population-based study. Total serum homocysteine (tHcy) was estimated in subjects attending the second Blue Mountains Eye Study (BMES) (n = 3509, aged >49 years). Its association with RVO (graded from retinal photographs) was examined. Homocysteine was more strongly associated with RVO in younger than older participants. In those aged <70 years, homocysteine levels >15 μmol/l were associated with increased odds of RVO, odds ratio (OR) 3.76; 95% confidence interval (CI) 1.06-13.40, in multivariable-adjusted analyses. Each 1 μmol/l increase in homocysteine was associated with a 7% increased odds of RVO, OR 1.07; CI 0.99-1.17 (P =. 08). This population-based study showed that elevated serum homocysteine is associated with the presence of RVO, independent of other risk factors.