Leukemia may involve almost any ocular tissue, by direct infiltration, by hemorrhage, and by ischemic changes. Both acute and chronic leukemia can cause ocular signs, either initially or later in the disease process; the clinical features and pathologic correlations of this involvement are reviewed. Also, various chemotherapeutic agents used to treat leukemia may cause ocular toxicity. Recently, bone marrow transplants have been performed more frequently in an attempt to prolong patient survival; if graft-versus-host disease results, one symptom is dry eyes from alacrima. Superimposed infection due to immunosuppression can occur from the disease itself or from treatment. Recognition by the ophthalmologist of the various ocular signs is important in assessing the course and prognosis of leukemia.