Myocarditis is marked by the infiltration of leukocytes in myocytes (heart muscles), while endocarditis is an infection of the inner lining and/or heart valves, usually of bacterial cause, which may or may not induce the formation of thrombi. Among the causes, infectious is prevalent, with Coxsackievirus B being one of the most common in the pediatric age group. The objective of this work is to report a case of myocarditis and endocarditis secondary to Coxsackievirus in order to train health professionals in the diagnosis and treatment of children with this pathology. A descriptive observational study was carried out by analyzing the medical records of a patient treated in the emergency room of a secondary hospital in the Federal District. To describe the case and discussion, a literature analysis was carried out in the UptoDate and American Heart Association databases, selecting the most relevant articles. The case reported is a male patient, 6 years old, previously healthy, who developed fever and asthenia seeking emergency care. In complementary exams, condensation of the middle lobe and cardiomegaly were visualized. With pneumonia and myocarditis suspected, the child was hospitalized and antibiotics were started. In subsequent investigations, thrombus/vegetation was identified on echocardiogram, increased D-dimer and serology with positive IgM antibodies to Coxsackie virus. He underwent treatment with Cefepime and Enoxaparin, showed clinical improvement and 4 months after diagnosis, the echocardiogram and serology for the virus in question were normal.