Monosomal karyotype has recently been reported to identify a distinct subset of acute myeloid leukemia (AML) with adverse prognosis.Patients with monosomal karyotype have unique clinical features and biological characteristics.The incidence of monosomal karyotype-AML increases with the age of patients.The most common single autosomal monosomy is the loss of chromosome 7 which is followed by the loss of chromosome 5.Patients with monosomal karyotype-AML have significantly worse overall survival,disease-free survival,and complete response compared with the patients with other unfavorable karyotypes.Monosomal karyotype is an independent prognostic factor for patients with AML receiving chemotherapy and allogeneic hematopoietic stem cell transplantation.New agents and treatment regimen need to be investigated.