Anticipatory nausea and vomiting, as a side-effect of cancer chemotherapy, is a well-recognised phenomenon known to affect a substantial minority of patients. Although explicable using a conditioning model, it may have a complex aetiology with affective and cognitive elements as well as specific pharmacological factors playing a role in its onset and maintenance. It is amenable to treatment using psychological techniques but to treat successfully it is important to understand the aetiology and formulate treatment plans according to those factors that make a significant contribution to the cause. It is suggested here that a behavioural model provides an over-simplistic conceptualization and that cognitive factors play a central role in onset. As such, treatment plans need to be broader in scope by focusing on a range of strategies to enhance coping and particularly cognitive coping techniques. More recently there has also been some indication that psychological factors may contribute to symptoms of nausea and vomiting occurring during or after chemotherapeutic infusion. Should this effect be replicated, the scope for psychological treatments within the care of patients receiving chemotherapy would be widened.