Since its initial description in 1893, alpha-chloralose has undergone extensive pharmacologic evaluation. It has been characterized as a compound possessing potent CNS activity and has been evaluated in humans and animal models for its therapeutic properties. Though the toxicity of the compound prohibits its use as a human therapeutic agent, it has been employed widely as an animal anesthetic in the laboratory setting. A thorough search of the literature reveals that alpha-chloralose is second only to sodium pentobarbital as the primary anesthetic agent in acute cardiovascular studies where the preservation of myocardial function is a primary consideration. The literature also shows that alpha-chloralose is the subject of much controversy. The question as to whether alpha-chloralose is a true anesthetic or an immobilizing agent with sedative-hypnotic properties has important implications in light of the current emphasis on ethics in animal research.