In intensively kept fattening pigs, biting is a vice complex of fairly common occurrence, of widespread distribution, of some economic importance but of obscure aetiology. It has been suggested that in any one particular outbreak of biting there may be more than one aetiological factor at work and that the behaviour may only occur when the sum of the individual effects of these factors goes beyond a certain critical (undefined) level (Ewbank, 1973). Factors such as: sub-optimal space allowance, temperature control, air movement, nutrients, palatability of feed, access to feed and water, can stimulate this kind of behaviour. Salt (NaCl) is an essential mineral and its rate of inclusion in diets has been implicated in the development and expression of biting behaviour. It is possible that heightened appetite for salt could make pigs particularly attracted to pen-mates with injured tails (Fraser, 1987). Although pigs require only about 0.2% NaCl in the diet for maximum weight gain, NaCl is often provided at 0.5% of the diet for growing pigs, and it has been suggested that an increase to 0.75% or 1% can reduce the incidence of biting. This paper investigates the influence of salt application on biting by growing-finishing pigs under an intensive indoor pig production system. An amount of extra salt was provided to the pigs and behavioural observations (biting, drinking, lying and standing) were recorded.