INTRODUCTION: A fenestration is an anatomical variation that most commonly involves vessels of the posterior circulation, which can predispose the formation of aneurysms and represents a further technical challenge for treatment. There are no large series and the incidence of complications is unknown. This paper is a systematic review on this topic. EVIDENCE ACQUISITION: The relevant English literature was reviewed and the data was extracted for each patient and collected in a pool. Demographics, localization of fenestration, morphology and aneurysm topography, admission and follow-up clinical status, treatments, complications and occlusion rate were recorded. EVIDENCE SYNTHESIS: We analyzed 62 articles published between 1992 and 2016 including 120/133 patients/aneurysms. The most commonly involved segment was the vertebro-basilar junction (82.5%), followed by the basilar trunk (10%). About 96.6% of reported aneurysms were saccular and 80.3% were ruptured. The preferred treatment was endovascular (86.67%) and a surgical clipping was reported in just over 13% of patients. A complete/almost complete occlusion was obtained in about 80% of cases, with a global rate of complications of 12.5%. A serious clinical condition at onset has been independently associated with poor outcome at multivariate analysis (P<0.001). CONCLUSIONS: This systematic review has shown that endovascular occlusion is the treatment of choice for posterior circulation aneurysms associated with fenestrations, being highly effective, with an occlusion rate of about 80%, unchanged at follow-up. Although the presence of a fenestration can make more complex the aneurysm occlusion, and the occurrence of complications is not negligible, it is not considered a limiting condition for treatment.