OBJECTIVE: To study the factors affecting the time to onset of ocular graft-versus-host disease (GVHD) in patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). METHODS: A retrospective chart review of 200 patients with ocular GVHD was performed to evaluate the association between various donor-recipient characteristics and the time to onset of ocular GVHD after allo-HSCT. RESULTS: The median time to onset of chronic ocular GVHD after allo-HSCT was 293 days (range, 26-2308 days). Patients receiving fully human leukocyte antigen (HLA)-matched transplants had a delayed onset of ocular GVHD (median, 294 days) compared with mismatched transplants (219 days; P = 0.029). HLA-matched transplants from related donors had delayed onset of ocular GVHD (307 days) compared with HLA-matched (286 days; P = 0.168) and HLA-mismatched (231 days; P = 0.015) transplants from unrelated donors. Ocular GVHD followed systemic GVHD in 76% of patients but preceded systemic disease in 7%, occurred concurrently in 15%, and was not associated with systemic GVHD in 2% of patients. The time elapsed between the occurrence of systemic and ocular GVHD was significantly longer in matched-related transplants (250 days) than in matched-unrelated transplants (120 days; P = 0.004). CONCLUSIONS: The onset of ocular GVHD after allo-HSCT is variable and is influenced by donor-recipient matching characteristics. In the majority of patients with GVHD, ocular involvement follows the occurrence of systemic manifestations; however, importantly, it can also precede or develop independently of systemic disease in a minority of patients. Regular ophthalmic follow-up is recommended after allo-HSCT regardless of concurrent systemic GVHD status.