Introduction and objectives: Breast cancer has been recognized as a major public health problem in the world. Is the most common cancer, and the leading cause of cancer death among women worldwide. The treatments include surgery, radiation, chemotherapy, hormone and targeted therapy. FAC-D protocol (5-fluorouracil, doxorubicin and cyclophosphamide, with docetaxel or paclitaxel) is the most common chemotherapy regimen in Brazil, and produces many adverse effects, which negative impact in the quality of life and in the treatment success. A Brazilian native fruit, açaí, has already been demonstrated to exhibit anti-inflammatory, antioxidant, anticancer and cardioprotective effects. Thus, the present study purposed to evaluation of the combined use of açaí and the FAC-D protocol in breast cancer model. Materials and Methods: Ethical approval by CEUA UEZO (No. 008/2014). Breast cancer was induced in 40 female Wistar by a single subcutaneous injection of 25mg/kg of 7,12-dimethylbenzanthracene (DMBA) in the mammary gland. Açaí treatment (200 mg/kg) or saline was initiated after 60 days, via gastric tube for 45 consecutive days. FAC-D protocol (5-fluororacil, doxorubicin, cyclophosphamide and docetaxel) were initiated after 105 days of induction, and administered by intraperitoneal injection for 3 cycles with 7-day break each. After treatment, the tumor (macroscopic and histological), heart (macroscopic, histological and immunohistochemical) and blood (leukogram, glycemia and biochemical) were collected for analyses. Results and conclusions: Breast tumor was found as a cystic mass and fibrotic pattern in the mammary gland. Histological analysis showed greater presence of inflammatory clusters in the saline group, however, in the invasive carcinoma area no differences was observed in both groups. No difference was noted in both groups based on body weight, glycemia, creatinine, urea, AST and ALT. However, açaí treatment decreased CK and CKMB levels and increased in the neutrophils number. Heart histopathological showed higher toxicity effects with loss of architecture of cardiac tissue in the saline group, and in the açaí treatment, showed normal myocardium histology. The picrosirius immunohistochemistry analysis revealed a greater marking in the açaí heart samples. These results demonstrated that açaí decreased inflammation in tumor environment and exhibit a protection of chemotherapy agent cardiotoxicity, supporting the use of açaí for an adjuvant treatment together with chemotherapy drugs.