The diagnostic work-up for the first syncopal episode of a 14-year-old female adolescent revealed the morphology of an isolated myocardial non-compaction on echography. Angiography and biopsy of the left ventricle confirmed the diagnosis. Despite a reduced shortening fraction (FS 21%) and frequent premature atrial beats, there were no further cardiac or extracardiac symptoms. After establishment of therapy with beta-blockade, digitalis, angiotensin converting enzyme inhibition and acetylsalic acid, the follow-up over 24 months was good; the implantation of an automatic implantable cardioverter-defibrillator is planned.