Reversible posterior leukoencephalopathy syndrome(RPLS)is a rare brain-capillary leak syndrome,characterized by clinical symptoms of headache,visual loss,seizures and altered mental functioning.This syndrome is usually reversible and is associated with hypertension,nephropathy,and use of immunosuppressive medication and cytotoxic agents.We describe two rare cases of RPLS occurring in colorectal cancer,both of which presented with coma,that we believe can be directly attributed to bevacizumab,a monoclonal antibody that inhibits the angiogenesis of tumours by specifically blocking vascular endothelial growth factor.We analysed the clinical features,risk factors and outcomes of RPLS in these two patients,and although no typical finding was identified on imaging examination,we found that inadequate blood pressure control was one of the risk factors leading to RPLS and that supportive treatment including intensive blood pressure control improved outcomes.Due to the increasing use of bevacizumab in colorectal cancer,clinicians should be aware of this potential complication. Reversible posterior leukoencephalopathy syndrome (RPLS) is a rare brain-capillary leak syndrome, characterized by clinical symptoms of headache, visual loss, seizures and altered mental functioning. This syndrome is usually reversible and is associated with hypertension, nephropathy, and use of immunosuppressive medication and cytotoxic agents. We describe two rare cases of RPLS occurring in colorectal cancer, both of which presented with coma, that we believe can be directly totributed to bevacizumab, a monoclonal antibody that inhibits the angiogenesis of tumors by specifically blocking vascular endothelial growth factor. We analyzed the clinical features, risk factors and outcomes of RPLS in these two patients, and although no typical finding was identified on imaging examination, we found that inadequate blood pressure control was one of the risk factors leading to RPLS and that supportive treatment including intensive blood pressure control improved outcomes.Due to the increasing use of bevaciz umab in colorectal cancer, clinicians should be aware of this potential complication.