Transient receptor potential vanilloid 1 (TRPV1) is a receptor for capsaicin, which is a main ingredient in hot chili peppers, and belongs to the TRP ion channel superfamily. Researchers have confirmed that TRPV1 is activated by multiple nociceptive stimuli including protons, noxious heat and some lipids both in the heterologous expression system using the cloned channels and native sensory neurons. In addition, studies using mice lacking TRPV1 revealed its importance at the behavioral level. Since 1997, when TRPV1 was first cloned, a considerable amount of information has accumulated regarding its agonists, the mechanisms involved in its activation and regulation, and the structural bases of these mechanisms. Furthermore, several clinical trials involving the use of TRPV1 antagonists as analgesic agents are currently underway. With success, some of these agents may enter the market in the near future.