The purpose of this study was to evaluate the efficacy of fish oil supplementation added to usual dry eye treatment in dry eye subjects in a randomized controlled trial. Twenty-seven typical dry eye subjects were selected from 43 candidates by the diagnostic criterion for dry eye in this study. They were assigned to the randomized fish oil group (n = 15) or the placebo group (n = 12). Fish oil group ingested fish oil capsules containing eicosapentaenoic acid (EPA, 1245 mg/day) and docosahexaenoic acid (DHA, 540 mg/day) for 12 weeks. Placebo group ingested placebo capsules without EPA or DHA. A visual analog scale test estimating subjective symptoms, the Schirmer I test, tear film break-up time (BUT) measurement, fluorescein staining, and rose bengal staining were performed every 4 weeks during the 12-week supplementation period and 4-week washout period. The subjective symptom of "eye pain", BUT, and changes in rose bengal staining score of the fish oil group were significantly improved after 8-12 weeks of supplementation and/or 4 weeks of washout, compared to those of the placebo group. These results suggest that fish oil supplementation added to usual care may be effective in the treatment of dry eye.