We present an unusual, biopsy-proven case of endomyocardial fibrosis in a 22-month-old male child, which progressed rapidly resulting in death. The patient was born to a father originating from Mozambique, where the disease is endemic but who had not himself travelled there, suggesting a genetic link. Other remarkable features were the presence of a right ventricular diverticulum, and a positive Mycoplasma pneumoniae immunoglobulin M enzyme-linked immunosorbent assay test.