Acute cerebellar syndrome can be caused by high doses of cytarabine, but it has not been described in patients with acute lymphoblastic leukemia (ALL) who received hyper-CVAD chemotherapy. Herein, we report two cases with histories of positive Philadelphia chromosome B-cell ALL who developed acute cerebellar syndrome after the exposure to relatively low doses of cytarabine in the second cycle of hyper-CVAD regimen. The cerebellar symptoms were attenuated by cytarabine discontinuation and administration of steroids. This case report provides detailed discussions on the treatments, the potential role of methotrexate in cytarabine-induced cerebellar syndrome, and the importance of carefully monitoring renal function during hyper-CVAD treatment.