Skeletal muscle extra-aortic counterpulsation was performed in seven dogs with dilated cardiomyopathy. A left latisslmus dorsi dynamic descending thoracic aortomyoplasty was used as the autologous counterpulsator. Pulse train stimulation In diastole was used to initiate contraction and fibre type transformation. Two of the dogs died within 48 hours of surgery. The device was successfully activated in the five remaining dogs, but in one individual it failed within 48 hours of activation. Serial echocardiographic examinations of dogs in which the device functioned successfully (n=4) showed trends towards the decrease In the left ventricular systolic Internal dimension, left ventricular diastolic internal dimension, E-point to septal separation and left atrial diameter in systole seven to 14 days following the procedure, although these changes failed to persist in the long term. The results suggest that skeletal muscle for cardiac assistances such as extra-aortic muscle counterpulsation, might be a therapeutic option for dogs with cardiac failure due to dilated cardiomyopathy.