Docetaxel is an important anti-microtubule agent used to treat a variety of solid tumors, including breast cancer; notably, docetaxel-containing regimens improve outcomes for patients in metastatic, adjuvant, and neoadjuvant settings. However, the effectiveness of docetaxel in clinical practice can be compromised by suboptimal management of side effects. Here, we report two cases of docetaxel-based chemotherapy regimens in patients who exhibited invasive ductal breast cancer and underwent two different clinical treatment approaches. A 58-year-old postmenopausal female received salvage treatment with 8 cycles of docetaxel (67 mg/m2), and a 74-year-old female received 1 cycle of docetaxel (100 mg/m2). The two patients exhibited considerable hearing loss two days later. Of note, both patients had no hearing loss symptoms prior to docetaxel. Thus, ototoxicity may be a side effect of docetaxel that should be considered during treatment.