This study is to investigate the significance of serum cardiac troponin for cardiac involvement in patients with immune-mediated necrotizing myopathy (IMNM). Methods: From September 2015 to December 2019, confirmed patients with IMNM admitted to Tongji Hospital were collected. The first serological results of the patients upon admission were obtained, including: cardiac troponin T (cTnT), cTnI, creatine kinase (CK), and the scores related to the activity of clinical myopathy, including Health Assessment Questionnaire (HAQ), manual music testing-8 (MMT-8), and myositis release activity assessment visual analog scale (MYOCT) scores. ECG, echocardiography, and cardiac magnetic resonance were used to distinguish patients with cardiac abnormalities from those without. The clinical data of the abnormal cardiac function group and normal cardiac function group were compared, and the relationship between cTnT and cTnI and cardiac involvement and disease severity was analyzed. Results: A total of 39 patients were enrolled into the study, with 25 patients in the normal group and 11 in the abnormal group. Serum cTnI in the abnormal group was significantly higher than that in the normal group (P=0.043). There was no significant difference in other serological indices (P>0.05). cTnI was significantly correlated with abnormal cardiac imaging (P<0.001); cTnT was significantly correlated with serum CK, MMT-8, and HAQ scores (P<0.001, P=0.010, P=0.036); serum CK was correlated with MMT-8 and HAQ scores (P=0.042, P=0.053). Conclusion: Serum cardiac troponins may have a role in screening for cardiac involvement in IMNM. cTnI may be valuable in assessing the severity of cardiac damage, while cTnT may be useful in determining the activity of immune-mediated necrotizing myopathy.