['Anticoagulants are commonly used to treat ischemic stroke. Its impact on cerebellar infarction has not been fully understood.', 'In the clinical study, we reviewed a consecutive series of patients with large-sized cerebellar infarction (diameter\xa0>\xa03\xa0cm, n\xa0=\xa030) treated with or without anticoagulation. In animal study, cerebellar infarction operation was performed in 12 Cynomolgus monkeys. Then the animals were administrated with low molecular weight heparin (LMWH) or vehicle for 14\xa0days.', 'Six patients died during the following treatment. All the subjects that died received anticoagulation therapy, while nobody in the survival group received such a therapy. Compared with sham-operated animals, all monkeys with cerebellar infarction have obvious neurological deficits. The number and size of the Purkinje cells in the cerebellar area were also reduced. Two animals in the LMWH group (33%) died, while all animals in the vehicle control group survived. Compared with the vehicle group, the neurological score in the LMWH group was significantly increased (P\xa0<\xa00.05). The water content in the cerebella was also significantly higher (P\xa0<\xa00.05). Edema, hemorrhage, and subarachnoid hemorrhage occurred in the cerebella as well as brainstem of all the LMWH treated animals.'] Is anticoagulation therapy harmful to large-sized cerebellar infarction?