The 5-HT6R is among the latest identified members of the 5-HT receptor family and is a particularly interesting receptor subtype because of its relatively low level of sequence homology (<50%) compared to other serotonin receptors. They include a short third cytoplasmatic loop and a long C-terminal tail, and one intron located in the middle of the third cytoplasmatic loop, as compared to most other serotonergic receptors. The 5-HT6R has shown enormous expectation as a drug target for the development of cognitive enhancers, based on localization, pharmacology, and behavioral data accumulated. Since cognition dysfunction is one of the primary manifestations of several neurodegenerative diseases such as Alzheimer’s disease (AD), the localization of 5-HT6 receptors in brain areas involved in learning and memory processes has identified this receptor as a putative target for AD.