Abstract： Objective To summarize the indication,method and effect of individual flexible endoscopic procedure for treatment of obstruction of fourth ventricle outlet.Methods The clinical data of 32 cases of obstruction of fourth ventricle outlet treated by individual flexible endoscopic procedure from July,2006 to June,2010 were analyzed retrospectively.Results Single endoscopic fourth ventriculostomy (EFV) was performed in 9 cases,EFV with endoscopic third ventriculostomy (ETV) in 5 cases,endoscopic aquductoplasty (EAP) with ETV in 5 cases,EAP with EFV in 2 cases,and single ETV in 11 cases.In cine phase- contrast magnetic resonance imaging( cine - MRI),26 (81.3％) cases showed fine circulation of CSF in aqueduct,10 (31.3％) fine circulation of CSF in Magendie's foramen and 15 (46.9％ ) fine circulation of CSF in the orificium fistulae of third ventricle floor.2 (6.3％ ) cases were symptomatic relief although unsatisfactory result appeared in postoperative cine - MRI.Of 5 ( 15.6％ ) cases who still suffered from postoperative intracranial hypertension,2 (6.3％ ) cases were released by external ventricle drainage for several days,3 (9.4％ ) cases had to had ventriculoperitoneal (VP) shunt because the intracranial hypertension could not be released.There was no complication related to operation appeared in all patients.Conclusions The obstruction of fourth ventricle outlet could be treated individually through trans - aqueduct approach via frontal key - hole with flexible neuroendoscope.Regular CSF circulation could be put back with shunt - free in partial patients,but the operative indication should be obeyed strictly.