Objective: To investigate the factors affecting the clinical prognosis and response to treatment in ocular graft-versus host disease fol- lowing allogeneic bone marrow transplantation. Material and Method: The demographic features, ophthalmologic examination findings, Schirmer I test measurements, tear break-up time, Oxford scores, medical and surgical treatment data were recorded, retrospectively. Results: Twenty-eight eyes of 14 patients (9 male, 5 female) were included. The mean age was 25.5 years (5-52); the mean time from al- logeneic bone marrow transplantation to the development of ocular graft-versus host disease was 22 months (8-84). Five patients had isolated ocular graft-versus host disease, while 9 had systemic involvement at the same time. All patients received the same standard top- ical treatment (preservative-free artificial tear preparations, cyclosporine eye drop). The mean follow-up period was 14,3±14,4 months (3-36). In 10 eyes of 5 patients with severe ocular findings had insufficient response to topical treatment and all of these patients had systemic involvement (3 had skin and gastrointestinal system, 2 had skin + gastrointestinal system and liver involvement). In 10 eyes with insufficient response to treatment, pre-treatment mean Oxford scores and tear break-up time measurements were Stage 4 (3-5) and 1 sec (0-5), while 18 eyes with sufficient response to treatment were Stage 2 (1-3) and 5 sec (3-7), respectively. Conclusion: Systemic involvement was observed a negative prognostic factor for the severity of ocular disease and response to treat- ment in patients with graft-versus host disease. Informing patients undergoing allogeneic bone marrow transplantation regarding ocu- lar symptoms may allow early diagnosis and treatment. Severe ocular findings in these cases may be a warning for systemic involvement.