Cisplatin (DDP) is one of the most frequently used chemotherapeutic agents, and has a characteristic toxicity profile. For DDP, complications affecting the cardiovascular system, which are typical for certain other agents, are rare; however, their occurrence may lead to life-threatening conditions. To the best of our knowledge, there are few reported cases of DDP-induced bradycardia in the relevant medical literature. The current report presents the case of a 58-year-old patient diagnosed with metastatic neuroendocrine carcinoma with a primary lesion in the posterior mediastinum, who was treated with DDP and etoposide chemotherapy. Following the initial chemotherapy cycle, the patient experienced severe symptomatic bradycardia (a drop in heart rate to 40 bpm), with the corrected QT interval prolonged to 424 msec. The patient's condition required close monitoring and treatment. Similar symptoms occurred following each of the three cycles of chemotherapy. Imaging studies performed following the third treatment cycle revealed disease progression, and the patient was referred for palliative care. Reports have indicated that damage to the cardiovascular system, including cardiac ischemia, diastolic disturbances, hypertension and microalbuminuria, may be associated with DDP-based therapy. However, the mechanism of DDP-associated cardiac toxicity remains to be elucidated. It may be induced by factors including direct toxicity, ion imbalance, heart infiltration and, in the case of neuroendocrine tumors, the influence of tumor excretions.