A group of 90 breast cancer patients undergoing chemotherapy were assessed prospectively to estimate the prevalence of acute (post-treatment) and anticipatory emesis in the 1990s. For this purpose, two protocols of chemotherapy were analysed separately: cyclophosphamide/methotrexate/5-fluorouracil (CMF) and 5-fluorouracil/doxorubicin/cyclophosphamide (FAC). All patients were treated with antiemetic therapy, which included one corticoid plus ondansetron (in the FAC regimen), or one corticoid plus thiethylperazine (in the CMF regimen). For at least one cycle of chemotherapy 86.1% and 91.7% patients in the FAC protocol presented vomiting and nausea respectively: 11.1% had anticipatory vomiting and 30.6% had anticipatory nausea. In the CMF protocol, 79.6% had post-chemotherapy vomiting and 71.7% had post-chemotherapy nausea associated with at least one cycle. In this group, 7.4% had anticipatory vomiting and 16.6% had anticipatory nausea. A high proportion of patients suffered anticipatory anxiety in both groups (75% in FAC, 74.1% in CMF). The stimuli most frequently associated with the appearance of anticipatory emesis were olfactory stimuli and cognitive stimuli. In summary, as a result of the advances made in antiemetic control during the last decade, the severity of chemotherapy-induced emesis seems to have significantly decreased, but the prevalence of these symptoms along the course of the treatment still remains high.