A 15 year-old male adolescent was hospitalized in a severe septic condition, due to infectious endocarditis which abided for 20 days. The admittance echocardiogram displayed a mitral valve vegetation in conjunction to a hypertrophic cardiomyopathy. In spite of applied antibiotics the patient expired. The authors emphasize the diagnostic difficulties of this compound entity and stress the need of antibiotic prophylaxis for patients who bear a hypertrophic cardiomyopathy, even in those with a non-obstructive disposition