Frequent premature ventricular complexes (PVCs) have been demonstrated to cause tachycardiomyopathy in some individuals with a structurally normal heart. We report a patient with severe congestive cardiomyopathy which did not respond to cardiac resynchronization therapy (CRT). Ambulatory monitoring and interrogation of the device memory revealed frequent monomorphic PVCs that were considered a potential cause of the failure of CRT. Radiofrequency ablation of the focus at the postero-inferior left ventricle eliminated the arrhythmia, with a resultant rapid improvement in the clinical status and echo parameters. As PVCs are often associated with severe heart failure, the presence of frequent extrasystoles may be an underrecognized cause of a non-response to resynchronization therapy.