Alterations in thyroid function are quite heterogeneous in VLBW preterm neonates. The case of a 1160-g newborn is reported, affected by severe RDS and persistent bradycardia during the first week of life, who later developed symptoms and signs of low-output cardiac failure. ECG showed low QRS. Echocardiography revealed small pericardial effusion. Therapy with L-thyroxine led to rapid improvement of clinical conditions and to normalization of ECG and echocardiographic pattern. Levels of thyroid hormones should be monitored in VLBW infants, since their deficiency may play a role in compromised clinical conditions.