A 76-year-old male patient with small cell lung cancer received EC (etoposide and carboplatin) chemotherapy combined with camrelizumab. On the 22th day of medication, the patient deve- loped chest tightness, shortness of breath, dyspnea, limb weakness, walking difficulty, etc. Laboratory tests revealed creatine kinase (CK) 1-210-U/L and CK-MB 63 U/L. The chemotherapy and immunotherapy were stopped, but the patient′s symptoms continued to worsen. Laboratory tests showed troponin T (TnT) 336-ng/L, CK 1-025-U/L, CK-MB 74-U/L, and N-terminal pro brain natriuretic peptide (NT-proBNP) 648-ng/L. The muscle magnetic resonance imaging (MRI) and electromyogram showed muscle injury and cardiac MRI showed left ventricular fibrosis. Then immune-related skeletal muscle and myocardial injury caused by camrelizumab was considered. The patient received an IV infusion of methylprednisolone sodium succinate for injection 100-mg once daily for 13 days. Then the patient′s fatigue symptoms were improved, the levels of CK and NT-proBNP decreased to the reference range, but the levels of TnT and CK-MB were 491-ng/L and 113-U/L, respectively. Therefore, an intravenous infusion of immunoglobulin 20 g once daily was given. Five days later, his dyspnea was improved, and TNT and CK-MB decreased to 201-ng/L and 59-U/L, respectively.