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130 patients with recent transmural myocardial infarction were studied in order to evaluate changes in left ventricular compliance. Left heart catheterization and cineangiographic left ventriculography were performed. The modulus of chamber stiffness (K) was determined from the slope of the linear relation between volume stiffness (dP/dv) and pressure; the modulus of muscle stiffness was evaluated by the Laird index (asymptotic slope of logP vs log V). Patients were divided in 3 groups: Group A included 5 patients studied before and after myocardial infarction who experienced an increase in the modulus of chamber and muscle stiffness after infarction. Group B included 10 patients who were studied at the onset of infarct and 15 days later: this group demonstrated changes in LV compliance with, most often a rightwardshift of P-V curve in anterior infarct and inversely a leftward shift in posterior infarction. The 115 patients of Group B are roughly equally distributed in the areas of normal, increased or decreased compliance. Any correlation was found between the extent of asynergy and changes in modulus of chamber stiffness. However, ejection fraction or VCF were higher in patients with a reduction of compliance than in patients with an increase of compliance.