Sigma receptors are promising drug development targets for a host of neurological, psychiatric, oncological, immunological, cardiovascular, ophthalmological, and gastrointestinal disorders. They are structurally unique proteins that are distinct from classical G protein-coupled receptors, ionotropic receptors, or receptor tyrosine kinases. With two subtypes currently known, they modulate cell survival and excitability, and subserve many critical functions in the body. Endogenous ligands for these receptors are unknown, though current clues point to neurosteroids. This book provides a timely update on the medicinal chemistry, cell biology, and clinical implications of sigma receptors. It puts the information in a historical perspective to help new comers to the field successfully navigate the confusing early history surrounding these proteins, and provides a launching point for the development of exciting, new research. Sigma Receptors: Chemistry, Cell Biology and Clinical Implications will be a valuable tool for pharmacologists, medicinal chemists, cell biologists, molecular biologists, clinicians, and others interested in a concise, state-of-the-art overview of the sigma receptor field with a particular view towards novel therapeutic advances.