Previous experimental research has demonstrated that patients can develop conditioned aversions to foods and beverages after a single pairing with chemotherapy administration for cancer. The present study used a prospective longitudinal design to examine the role of posttreatment nausea in the development of learned food aversions in these patients. Chemotherapy patients sampled a distinctive beverage immediately prior to their first and second chemotherapy infusions. We assessed nausea, and other chemotherapy side effects, for the 24-h period following chemotherapy administration. Food aversion, at the second infusion, was assessed in terms of behavior (decreased consumption) and affect (decreased hedonic rating). Consistent with previous research, patients showed both decreased consumption and decreased hedonic rating after a single chemotherapy infusion. Nausea was found to be related to decreases in hedonic rating, but not to decreases in consumption. No other treatment side effects predicted either decreased consumption or hedonic rating. These results are consistent with the hypothesis that there is a special link between nausea and changes in affective response to food items. These results also highlight the unique opportunities for studying food aversion formation in the oncology setting.