Eye disorders are one of the characteristic adverse events associated with S-1 chemotherapy. In this retrospective study, we investigated the frequency and outcome of eye disorders associated with S-1 chemotherapy in gastric cancer patients. This retrospective study included 75 advanced gastric cancer patients who received S-1 monotherapy between January 2014 and December 2015. We retrospectively evaluated the frequency, Grade, and treatment of eye disorders. Eye disorders were observed in 16 patients(21%). The median time of onset was 3(range, 1-8)months. Grade 2 watering eyes, eye discharge, and conjunctivitis were reported in 14, 8, and 4 patients, respectively. Artificial tears, fluorometholone eye-drops, and both of these treatments were used in 7, 1, and 8 patients, respectively. Ophthalmologic examination was performed for 3 patients. No delay or reduction of S-1 therapy was required for the eye disorders. Eye disorders associated with S-1 therapy in gastric cancer patients did not affect treatment if managed properly using eye drops.