Background: Under physiological conditions, the myocardial extracellular matrix (ECM) is maintained by matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). However, certain stimuli cause the upregulation of MMPs, which can lead to pathological remodeling of the ECM. We assessed serum levels of MMPs and TIMP-2 in patients with myocarditis and their relationship(s) to myocardial damage.Methods: In total, 45 patients with myocarditis who underwent cardiac magnetic resonance imaging were included, comprising 11 with concurrent chronic kidney disease (CKD). Blood samples were obtained to assess serum levels of MMP-2, MMP-3, MMP-9, and TIMP-2. Results: Serum MMP-2, MMP-3, and TIMP-2 levels negatively correlated with ejection fraction values in patients with myocarditis, while MMP-3 levels correlated with longitudinal deformation (p<0.05). Serum MMP-2, MMP-3, and TIMP-2 levels also negatively correlated with renal function, as assessed by the estimated glomerular filtration rate (p<0.05). Patients with myocarditis and concurrent CKD had higher levels of MMP-2 and TIMP-2 than those without kidney damage.Conclusions:1. We demonstrated serum MMP-2, MMP-3, and TIMP-2 concentrations were related to left ventricular ejection fraction, and MMP-3 levels correlated with longitudinal deformation, indicating MMPs play an important role in the post-inflammatory remodeling of the myocardium.2. The occurrence of other heart diseases was an important element in modifying the relationship between MMPs and the degree of myocardial damage.3. Chronic kidney damage in patients with myocarditis results in increased MMP activity. A negative correlation between eGFR and MMP-2, MMP-3 and TIMP-2, and a positive correlation between creatinine and MMP-3 levels, underlines the role of fibrosis in myocarditis with concomitant chronic kidney disease.