Many studies of ventricular structure and function of the hypertrophied cardiac muscle have been performed using a model of right ventricular hypertrophy because a reliable experimental model for the chronically hypertrophied left ventricle was not available. Adult rabbits underwent thoracotomy with placement of an ameroid band on the proximal aorta. The ameroid band closed to a maximal extent at 9 days. Systolic gradients were measured at 3 weeks. 37 animals (group I) were sacrificed at an average of 7 weeks, and 5 (group II) at 18 weeks. Specific cardiac chambers were weighed. The average left ventricular weight expressed as a percentage of body weight of control animals was 0.13 ± 0.01 compared to group I 0.17 ± 0.04 (p =0.001) and group II 0.23 ± 0.04. Hemodynamic data revealed significant aortic outflow obstruction with systolic gradients averaging at least 50 mm Hg. Left ventricular end-diastolic pressures were elevated in 13 of 29 animals compatible with left ventricular failure. These results indicate that this technique affords a reliable experimental model for inducing biventricular hypertrophy which can be evaluated hemodynamically.