ICA dysgenesis is a rare finding and whose aetiology is not yet fully elucidated. Collateral circulation is very common; hence it is usually an incidental finding. Collateral circulation is under significant hemodynamic stress and therefore intracranial aneurysms are frequent in cases of ICA dysgenesis. We report the case of a 57-year old female who presented with headache and right ICA agenesis with associated anterior communicating segment aneurysm and azygos (unpaired) A2 segment. To the best of our knowledge this rare anatomic variant has not been reported. These patients should undergo thorough investigation for intracranial aneurysms and should receive prompt treatment. To date there is not enough information as to indicate specific treatment for aneurysms in these patients.