Duchenne muscular dystrophy (DMD) is a severe X-linked hereditary disorder resulting from mutations in dystrophin gene (DMD) and leading to progressive degeneration of skeletal and cardiac muscles. Classic clinical phenotype is characterized by progressive motor dysfunction and muscle weakness, while cardiac involvement typically presents as dilated cardiomyopathy accompanied by arrhythmias and conduction disturbances. This report describes a patient who developed severe dilated cardiomyopathy at 12 years of age with left ventricular ejection fraction 21%. Despite optimal therapy the patient experienced recurrent heart failure decompensations (up to 8 times annually) between 12 and 18 years of age. Genetic analysis at 18 years of age identified pathogenic DMD gene mutation, and Duchenne muscular dystrophy was diagnosed. Although heart transplantation was deliberated, the patient succumbed before evaluation by a transplant team. This case underscores the importance of early etiological diagnosis in dilated cardiomyopathy, awareness of cardiologists regarding Duchenne muscular dystrophy and timely initiation of disease-specific treatments. Detection of DMD mutation warrants comprehensive cardiovascular screening, regular cardiological follow-up and genetic counseling.