History and Admission Findings: We report on a case of a 31-year-old patient who was admitted to hospital with acute cardiac failure. At physical examination we found peripheral edema and wet rales., Investigations: Cardiac ultrasound revealed severely impaired left and right ventricular function and prominent trabeculation in the right ventricle, but also in the apex of the left ventricle. This was confirmed by cardiac magnetic resonance imaging. Both pulmonary embolism and coronary heart disease were excluded by thoracic computed tomography and coronary angiography., Diagnosis, Treatment and Course: These findings were in line with the diagnosis of non-compaction cardiomyopathy resulting in cardiac failure. We introduced diuretic therapy which leads to weight loss and release of dyspnoea. Due to prevention of embolic events an anticoagulative therapy was started. In light of rhythmogenic vulnerability, a subcutaneous implantable cardioverter defibrillator (ICD) system was implanted. Afterwards the patient was discharged in good general health., Conclusion: Non-compaction cardiomyopathy (NCCM) is a hereditary non-ischaemic cardiac disease which occurs due to the failure of myocardial compaction during embryogenesis. Common manifestation is the triad of heart failure, rhythmogenic vulnerability and systemic embolic events. First-line imaging technique for diagnosing NCCM is cardiac ultrasound. The prognosis depends on severity of heart failure, ventricular arrhythmia and the incidence of embolic events., (© Georg Thieme Verlag KG Stuttgart · New York.)