Hypereosinophilic syndrome (HES) is a rare disorder typically seen in males, aged 20 to 50, with a predisposition for Caucasians. It is marked by overproduction of eosinophils (>1,500/μL) and multiorgan system damage due to eosinophilic infiltration and mediator release. There are multiple variants of HES. Cardiac complications are more common in myeloproliferative HES associated with the FIP1L1-PDGFRα mutation. Sequelae range from acute necrosis and thrombus formation to fibrosis of the endomyocardium. We describe a young boy who presented with chest pain and dyspnea. A diagnosis of HES was made after all other etiologies of eosinophilia were excluded. Although he was found to be negative for the FIP1L1-PDGFRα mutation, his cardiac complications included pericardial effusion and restrictive cardiomyopathy, without myocardial necrosis. Multi-organ involvement resulted in pericarditis, pleuritis, nephritis, and dermatitis. In this paper, we review his case and discuss the known subtypes of HES, the classic cardiac complications, and available treatment strategies.