Objective: To investigate the histopathological and ultrastructural features of arrhythmogenic cardiomyopathy (ACM). Methods: The clinical and pathological data of 38 ACM patients with heart transplantation were retrospectively studied, the clinical characters, gross observation and histopathological findings were analysed. e correlation between the histological type, myocardial ultrastructure changes and clinical electrocardiogram performance in seven cases were identi ed using transmission electron microscopy. Results: Classical right- dominant subtype (57.9%) was the most common, followed by biventricular forms (31.6%), then le -dominant subtypes with predominant LV involvement (10.5%). The histological changes of classical right-dominant subtypes were mainly fatty replacement, and that of the left dominant subtypes were mainly fibroadipose replacement (P<0.05). Transmission electron microscope found that sarcomere supercontraction, overstretch or myo bril fracture were ubiquity, and abnormality intercalated discs were observed in 85.7% (6/7), immature myocardial cell or organelles could were observed in 71.4%. Patients of classical right-dominant subtypes were younger than that of the other two groups (P=0.02). Arrhythmia types were associated with anatomical classification (P=0.01). The incidence of ventricular arrhythmias: biventricular (88.9%) > RV-dominant (42.3%) > RV-dominant (0%). Histologic changes of left ventricular associated with heart weight increased (P<0.01). The left ventrical ejection fraction (LVEF) did not show a relationship with anatomical type or hishistopathological type(P>0.05). Conclusion: Histological and ultrastructural examination on ACS could help the etiological diagnosis, and also provide the morphological basis for further genetic studies.