Introduction: Posttreatment nausea (PTN) is a common side effect of cytotoxic cancer chemotherapy. Previous retrospective research has suggested that the severity of PTN may be, in part, related to pretreatment psychological factors (e.g., emotional distress and expectations for nausea). Materials and methods: The purpose of the present study was to examine these relationships prospectively, with distress and nausea expectations assessed by validated self-report measures completed in the clinic before the participants' first outpatient treatment infusion and with PTN (0-100) assessed by end-of-day diaries completed at home on each of the first 5 days after treatment. The participants were chemotherapy-naive women (N=56) scheduled for standard adjuvant treatment for stage I-II breast cancer (mean age=45.6 years). PTN was evaluated for acute (days 0-1) and delayed (days 2-5) responses. Results: The results revealed a significant relationship between pretreatment distress and the severity of the patients' subsequent delayed nausea (p<0.007) but not a relationship with acute PTN (p<0.19). No significant relationships were seen between expectations and PTN. However, there was evidence of an additive effect of nausea expectations and distress, with the highest levels of delayed PTN seen in patients with both expectations and higher distress before treatment. The results suggest a selective effect of pre-infusion psychological variables on the delayed phase of nausea after chemotherapy, consistent with an emerging view that the different phases of nausea are mediated by different neural pathways. Conclusion: Future research should examine the possibility that delayed nausea, which the literature suggests is more resistant to antiemetic drugs than acute nausea, might be responsive to psychological interventions before initial treatments.