AIM:Abnormal transparent septum is common in clinical works but little in meaning,so some CT reports are not listed.We collected complete abnormal transparent septum cases to perform comparison analysis between CT diagnosis and clinical data.METHODS:109 abnormal transparent septum diagnosed by CT was compared with symptom of clinics.Axis scanning and no enhanced scanning were used in CT and 2 doctors in charge of sample collection.The 109 cases were excluded with abnormal transparent septum induced by secondary local cerebral atrophy and secondary perforation deformity.RESULTS:There were 15 cases with the fifth ventricle of cerebrum and 22 cases with the fifth and sixth ventricle of cerebrums,10 cases with transparent septum cyst,28 cases with translocation of transparent septum,8 cases with no crack in the forebrain,6 cases with poor development of keratoma and 20 cases of other deformity.CONCLUSION:Abnormal transparent septum cannot be omitted and should be clearly diagnosed by CT.