Objective To explore the relationship of vertebral artery hypoplasia (VAH) with acute posterior circulation cerebral infarction (APCCI).Methods One hundred and eighty-nine consecutive patients diagnosed as having acute cerebral infarction admitted to our hospital from March 2015 to March 2016 were enrolled in our study;retrospective analysis was performed on their clinical and radiographic data to compare the general clinical characteristics of patients with posterior circulation infarction (PCI) and anterior circulation infarction (ACI).VAH was conformed by cranial magnetic resonance angiography (MRA),vertebral artery ultrasound or cranial MRA+vertebral artery Ultrasound.The infarction lesions in VAH patients with APCCI were typed;the correlation between vertebral artery diameter's differences and National Institute of Health stroke scale (NIHSS) scores in VAH patients with APCCI was illuminated.Results In 189 consecutive patients with acute cerebral infarction,32 (16.93％) were with VAH;after exclusion of 8 with infarction in both anterior and posterior circulation,90 (49.72％) were in PCI group while 91 (50.28％) in the ACI group.Univariate analysis showed that statistical differences were noted between the two groups in triglyceride (TG) and VAH levels (P＜0.05).In 23 patients with APCCI with VAH,brain stem infarction consisted of 9 patients (5 VAHs were ipsilateral to the infarction,3 VAHs contralateral and one bi-VAH),cerebellum infarction consisted of one patient (ipsilateral side),thalamus infarction 10 patients (4 VAHs were ipsilateral to the infarction,and 6 VAHs contralateral),occipital lobe infarction 2 patients (one ipsilateral and one contralateral) and cerebellum with thalamus infarction one patient (the side of VAH was ipsilateral to the cerebellum and contralateral to the thalamus).After excluding one patient with bi-VAH,in 22 patients with APCCI combined with VAH,significantly positive correlation between vertebral artery diameter's differences and NIHSS scores was noted (r=0.560,P=0.000).Conclusions It might be the best assessment standard of VAH measured by combination of transcranial MRA and vertebral ultrasound.TG and VAH may be risk factors of APCCI,and VAH could be one independent risk factor of APCCI.The side of VAH is usually ipsilateral to the brain stem and cerebellum infarction,while contralateral to the thalamus infarction in APCCI patients with VAH.Also,vertebral artery diameter's differences are positively correlated with NIHSS scores.