Background Acute myeloid leukemia (AML) with t(8;21) is generally associated with a favorable clinical course. Loss of sex chromosome (LOS) are frequently observed in t (8;21) AML, but the prognostic value of LOS remains uncertain.Methods A total of 73 patients with AML with t(8;21) were studied and divided into t(8;21) with LOS group (n = 36) and t(8;21) alone group (n = 37). The patients with t(8;21) AML with ACAs other than LOS were excluded. The clinical characteristics of these two groups were compared, and the prognostic value of LOS was evaluated based on disease-free survival (DFS) and overall survival (OS).Results The clinical characteristics (except for gender) were found to have no significant difference between these two groups, and the male patients tended to account for a larger proportion in the former group (P = .001). The OS of the t(8;21) AML with LOS group was significantly longer than that of the t(8;21) AML alone group (P = .005). While not obvious, the patients with LOS seemed to have longer DFS (P = .061). The multivariable analysis also showed LOS to be an independent favorable prognostic factor of t(8;21) AML (P = .022).Conclusions Our results suggested that LOS could be associated with a favorable prognosis in t(8;21) AML patients without other ACAs, and for this subtype of AML, longer DFS and a satisfactory and stable survival can be achieved with high-dose cytarabine (HDAC) consolidation treatment.