Patients who agreed to participate in the study were submitted initially to a screening interview with the Brief Fatigue Inventory questionnaire from MD Anderson. If the patient presented with a severe fatigue, anemia (HB<11.0), hypothyroidism or psychiatric disorders she was excluded. If she presented with a mild or moderate fatigue the follow up continued and the patient was assessed 21 days later after her first cycle of chemotherapy with the same questionnaire. If an increase in fatigue levels occurred from mild to moderate, mild to severe or moderate to severe the patient was randomly assigned to receive either Guaraná 50mg or a placebo p.o. q12 for 21 days. At this moment the patient answered a General questionnaire, FACIT-F, FACIT-ES, HADS, Pittsburgh Sleep Quality Index and Chalder Fatigue Questionnaire (Day 1).