An increasing number of patients with malignant lymphoma are becoming long-term survivors following treatment with chemotherapy (CT) and/or radiotherapy (RT). Therefore, late therapy-related complications are becoming increasingly clear. We present three young patients to illustrate the dire consequences of late-onset cardiotoxicity as sequel to potentially curative treatment. We advise yearly life-long follow-up of CT/RT patients treated with curative intent. Echocardiography should be performed when cardiac murmurs arise. Prevention of further cardiac damage by reducing other cardiac risk factors as well as endocarditis prophylaxis when indicated is recommended.