The ability to assess the level of unconsciousness (insensibility) in poultry is important on farms and in abattoirs, where the effectiveness of stunning and slaughter needs to be ascertained. Moreover, knowledge of the most reliable indicators of insensibility is essential to producers and researchers responsible for maintaining acceptable levels of poultry welfare. A problem with assessing insensibility in poultry is that no single method is appropriate under all circumstances, and some methods are not practical in field situations. Several measures have been recommended and used to evaluate insensibility in poultry, including brain stem reflexes, such as the corneal reflex, and spinal reflexes, such as the pain withdrawal reflex. This review examines specific advantages and disadvantages of measures that have been used to assess insensibility in studies of killing methods, and provides an overview of recommended …