Objective To investigate the association between obstructive sleep apnea-hypopnea syndrome (OSAHS) and transient ischemic attack (TIA) in posterior circulation and related pathogenesis.Methods A total of 30 patients with TIA in posterior circulation who were hospitalized and treated in our hospital were enrolled as case group, and 34 patients without TIA in posterior circulation were enrolled as control group. The general clinical data and the results of polysomnography were collected for all patients. The distribution characteristics of varying degrees of OSAHS in two groups were analyzed retrospectively. The binary logistic regression analysis was used analyze risk factors for TIA in posterior circulation and its association with OSAHS, and the Spearman correlation test was used to investigate the association between OSAHS and risk factors for TIA in posterior circulation.Results A total of 24 patients in the case group and 18 in the control group had OSAHS, and there was a significant difference between the two groups (P<0.05); 11 patients in the case group and 2 in the control group had severe OSAHS, and there was a significant difference between the two groups (P<0.05). Severe OSAHS was associated with TIA in posterior circulation. Diabetes, low-density lipoprotein, triglyceride, body mass index (BMI), homocysteine (Hcy), and smoking were independent risk factors for TIA in posterior circulation, while OSAHS was not an independent risk factor for TIA in posterior circulation. OSAHS was significantly associated with smoking, hypertension, BMI, and Hcy.Conclusions OSAHS is a risk factor for TIA in posterior circulation, but it is not an independent risk factor. OSAHS promotes the development of TIA in posterior circulation by interacting with other risk factors such as smoking, hypertension, BMI, and Hcy.