Nausea, vomiting and anxiety related to administration of cancer chemotherapy remain significant problems. This randomized, clinical trial was undertaken to evaluate the effect of sedation on the patient's comfort during chemotherapy infusion in patients with breast cancer. Forty-five breast cancer patients were randomized into three groups: Group I - chemotherapy, control, Group II - midazolam+chemotherapy, and Group III - propofol+chemotherapy. Nausea occured in 87% and vomiting in 13% of the patients in the control group, while none of the sedated subjects had these side-effects, although 76% of them had experienced then during previous cycles of chemotherapy. Compared with the control group, post-chemotherapy anxiety scores also improved with the addition of midazolam or propofol. Eighty percent of the subjects declared that they would prefer the sedative-containing regimen for their further cycles. Sedation with midazolam or propofol may improve the patient's comfort, and provide better control of chemotherapy-related side effects during chemotherapy infusion in breast cancer patients.