Erdheim-Chester disease (lipoid granulomatosis) is a rare type II (non-Langerhans cell) histiocytosis with systemic manifestations. The disease causes nonspecific disturbances in the function of multiple extraosseous organs, most commonly the eyes, lungs, pituitary gland, and kidneys. Diagnosis is usually made on the basis of radiologic evidence of cortical expansion of long bones. While the osseous and systemic changes have been well documented in the current literature, pathologic changes in the myocardium have not been well characterized since Erdheim and Chester's first description of this disease in 1930. In the 2 autopsy cases from Dartmouth-Hitchcock Medical Center (Lebanon, NH) reported in the present study, myocardial involvement was severe and had contributed significantly to the patients' morbidity and death. We describe the autopsy results and correlate them with Erdheim's original descriptions of this disease. In neither of our cases was bony involvement characteristic of the disease, and the diagnosis was made postmortem on the basis of soft tissue findings at autopsy.