The patient, who was being followed-up with the diagnosis of Pre-B ALL, had two allogeneic bone marrow transplants, developed Graft- Versus-Host disease after peripheral blood stem cell transplantation, and had a history of ruxolitinib and high-dose dexamethasone usage, was consulted with decreased visual acuity while hospitalized in hematology clinic due to necrotizing fasciitis on his foot. Intrathecal chemotherapy and dexamethasone treatment were recommended to the patient who had a bilateral serous macular detachment in ophthalmologic examination and leukemic infiltration of the choroid that was suspected in his ocular imaging. It was observed that the patient?s vision improved, and the serous detachment regressed after the addition of dexamethasone to ongoing ruxolitinib treatment. Serous retinal detachment is a rare finding in ALL. This finding may indicate choroidal infiltration and poor prognosis. Therefore, early diagnosis and treatment are very important to improve the prognosis. Keywords : Acute lymphoblastic leukemia, serous macular detachment, leukemic infiltration, Graft-versus Host, peripheral blood stem cell transplantation