Objective:To explore the feature of impaired sustaind attention in the stable patients with bipolar disorder and their first degree relatives.Methods:Totally 76 patients with bipolar disorder meeting with, 83 first degree relatives of patients and 81 healthy controls, were employed and evaluated with continuous performance test (CPT).Results:In reaction time task (a simple performance), all of CPT parameters were higher in patients group than in the first degree relatives group and controlled group (Ps＜0.01), while all of CPT parameters in the first degree relatives group were similar to those in healthy controls (Ps＞0.05).In X task (a complex performance), the results of CPT in the first degree relatives group were between the patients and the normal controls, and the differences were statistically significant (Ps＜0.05).Conclusion:The sustained attention function may have a certain hereditary apparent in stable patients with bipolar disorder.