Abstract： Paraneoplastic neurologic syndromes (PNSs) occur with increased frequency in patients with cancer and almost always antedate its diagnosis.These syndromes comprise a heterogeneous group of cancer-related neurologic diseases,and they may affect any part of the nervous system.The simultaneous involvement of different areas of the nervous system by the paraneoplastic process is not unusual.Until date,this is the first report of concurrent development of paraneoplastic cerebellar degeneration (PCD) and paraneoplastic limbic encephalitis (PLE) associated with the advanced ovarian cancer and anti-Yo antibodies following hepatitis B (HB) vaccination.The cause of most PNS is believed to be an immune response against neuronal proteins expressed by the tumor.