Summary The prevalence of nausea and emesis among a series of out-patients (n = 95) receiving mainly mildto moderately-emetic cytotoxics, was assessed, along with levels of psychological morbidity. Particular focus was given to the rates of psychologically-based (anticipatory) nausea and emesis. Results indicated that 23% of patients experienced anticipatory nausea and the majority reported that this occurred before at least half of the previous treatment cycles. Both There is also an increasing literature showing that some patients receiving CT develop psychologically-based nausea and emesis (Watson & Marvell, 1991). Although this may occur before, during or after administration of CT most studies examine anticipatory symptoms, as the psychological effect is more difficult to distinguish from purely drug-related effects at other times. However, post-treatment nausea and emesis which is out of proportion to the emetic challenge of the CT drugs may well indicate a psychological element and this effect is less well researched.Although occurring less commonly than post-treatment nausea and emesis, the importance of the anticipatory sideeffect lies in its intractability once established and the fact that it may continue after CT administration has ceased, with some patients feeling nauseous when they return for followup out-patient appointments (Hughson & Cooper, 1988). Furthermore, it is assumed that with the advent of the 5-hydroxytryptamine3 (5-HT3) antagonists, not only will post-treatment side-effects be controlled, but anticipatory symptoms should become a thing of the past. However, control using 5-HT3 drugs is not always complete (Jones et al., 1991;Smyth et al., 1991) and as yet there are no published studies which examine the prevalence of an anticipatory nausea and emesis response where 5HT3, drugs were used, although clearly such studies are needed.The most widely accepted explanation for anticipatory/ psychologically-based nausea and emesis is that it is a conditioned (i.e. learnt) response. Neutral stimuli present at the time of CT administration, and associated with the druginduced effect, acquire the ability to trigger nausea and/or emesis during subsequent treatment cycles, even when the drug has not yet been administered. In psychological terms this is a very simple learning paradigm and the effect has also been observed in sub-humans.A number of studies have drawn attention to the possible role of anxiety as a contributory factor (Altmaier et al., 1982;Andrykowski et al., 1985;Nerenz et al., 1986). It is intuitively appealing to explain psychologically-based nausea and emesis in terms of 'nerves' yet it is clear from Andrykowski's recent review (1990) Other possible risk factors potentiating psychologicallybased nausea and emesis include a tendency to travel sickness in adulthood, and younger age (Morrow et al., 1991). The clearest contributor, however, is thought to be severe and long-lasting nausea and emesis following previous CT infusions. Thus it is likely that the toxicity of the drug re...