The immune system is a dynamic, reactive surveillance system. Some genes influence immune responses, cell to cell communication which either facilitate or protect against neuroimmunological disorders. Dysregulation at this level seems to have a role in a large spectrum of neurological disorders opening up a new window to therapy. A good number of syndromes are definite entities, and others are probable in this group. Clinically subacute encephalopathy with diarrhea, ovarian teratoma, facio-brachial dystonic seizures, and the triad of panic, catatonia, and sleepiness are classical pointers. EEG is mostly non-specific except for the extreme delta brush of NMDA and helps differentiate the immediate differential diagnosis of SSPE, CJD, and HSV. Imaging has patterns recognizable in conditions like clippers or can be normal. Antibodies seem to be the definite tool, but there can be unknown antibodies. A high degree of suspicion is important for diagnosis.