Various studies have shown that rodents avoid the odour of stressed conspecifics, of blood and of predators. The present study assessed the behavioural response to various biologically significant odours in cattle. Prior to experimentation, cattle were trained during 15 days to walk through a corridor for food. In the middle of the corridor, at either side, two ventilating odour dispensers were fixed behind perforated screens. The odours of urine from nonstressed and stressed conspecifics and of blood were studied in the first series of test, those of water and dog faeces in the second series. During experimentation, the odour dispensers contained the relevant biological substances (`odours') or no substance (`controls'). Behaviour was recorded until 5 min following food intake. The odour of water did not induce changes in behaviour. The odours of urine from nonstressed conspecifics, of urine from stressed conspecifics, of blood and of dog faeces caused similar increases in postfeeding sniffing air. The last three odours induced, in addition, similar amounts of postfeeding stretched locomotion. The day after testing with either of these three odours, when exposed to the test environment without odour, cattle still showed increased postfeeding sniffing air. Dog faecal odour was the only odour to induce behavioural changes prior to feeding, involving also an increase in sniffing air and in stretched locomotion. The results may suggest that sniffing air is the more general response to an odour added to the environment, and that stretched locomotion is the behavioural expression of the perception of an odour that indicates a potential danger. Alternatively, despite their similarity, the responses may not reflect similar motivations. The different odours evoked further, a number of qualitatively different responses, suggesting that cattle attribute at least to a certain extent different meanings to the different odours.