Although anaesthetic techniques are well established for most of the vertebrates, methods for the invertebrates are generally not well documented. The decapod Crustacea are widely used for neurophysiological studies involving the implant of chronic electrodes and other techniques. With sluggish species such as Cancer pagurus some workers simply give the animal an object to grasp and perform their operations in the unanaesthetized condition. Others use hypothermia to immobilize their animals, although this may result in autotomy of appendages. Other methods include immersion in solutions of ethanol, magnesium salts (Pantin, 1946), or carbon dioxide. Conventional aquatic vertebrate anaesthetics such as MS-222 (Sandoz) are generally ineffective by immersion in decapods. This short investigation has set out to find out if a suitable anaesthetic drug is available for experimental work and for live dissections.