Paraneoplastic limbic encephalitis (PLE) is a rare disorder and it is also under-reported due to the difficulty in establishing the diagnosis. The delay in treatment could potentially lead to devastating neurological outcomes. The authors report a 32-year-old Caucasian, nullipara woman, who presented with a subacute dementia associated to generalized tonic-clonic seizure with rapid progression to coma. The diagnosis of immature ovarian teratoma surgical Stage FIGO IA R0 with PLE was confirmed. The patient began earlier oral corticosterois and human intravenous immunoglobulin. She was discharged one month after surgery with no neurologic deficit and remains three years later in oncological remission. A diagnosis of PLE should be considered in the differential diagnosis of unexplained dementias. Early diagnosis, treatment of the underlying malignancy, and prompt intervention with immunotherapy in this patient at the onset of presentation facilitated regression of the neurological syndrome and explains the favorable neurological outcome.