The study design involved case reports and review of the literature. Oncotic aneurysm from choriocarcinoma is an extremely rare event that should be known by all neurosurgeons and suspected in women of childbearing age. The purpose of this article is to report the authors' experience and to provide insight on clinical presentation and radiological signs to aware the reader to this entity and then to prevent misdiagnosis. The authors report two cases of ruptured oncotic aneurysm treated at their institution in 2010. A review of the literature was performed to discuss the pathogenesis and the role of the neurosurgeon. Chemotherapy is the treatment of choice making surgery necessary only for patients with large intracerebral haematoma that represents an immediate threat.