This chapter gives an overview of the syndromes associated with antibodies directed to membrane-bound or synaptic proteins. In contrast to the classical syndromes, disease occurs in younger patients as well; patients are also seen by non-neurologists like psychiatrists and pediatricians, and patients tend to have a more favorable response to immunotherapy. The focus in this chapter is on the clinical characteristics which distinguishes these disorders and on the relevance of cerebrospinal fl uid (CSF) analysis. Comparison of sensitivity and specifi city for serum and CSF is extensively discussed. N -methyl-D-aspartate receptor (NMDAR) encephalitis is relatively common and discussed fi rst. Alpha-amino- 3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) encephalitis and encephalitis associated with antibodies to the metabotropic glutamate receptors mGluR1 and mGluR5 are rare and will be reviewed briefl y. Subsequently, syndromes associated with antibodies to the glycine receptor, VGKC complex, and dipeptidyl-peptidase-like protein-6 (DPP6) are described. Encephalitis with antibodies directed to the a-aminobutyric acid (GABA) receptor type B and type A are reviewed last.