Residual strain in a systolic heart was measured in equatorial ring like slices of canine left ventricles arrested in systole with barium. Global and two-dimensional local strains were computed from the deformation of each slice following its radial cutting. Global circumferential strain in the epicardial surface was 1.033±0.037 (mean±SD) and was significantly larger than that in the endocardial surface (0.985±0.052), corresponding to opening-up of the ring like slice after the radial cutting. Local strain distribution through out the wall thickness differed from position to position and from specimen to specimen, although cumulative data showed that local circumferential strain was distributed similarly to the global strain. Histological observation showed that large tensile strain appeared preferentially in the area where myocardial fibers run in the circumferential direction and that the strain was generally compressire in other areas. The residual strain in the systolic heart may be closely correlated with the orientation of myocardial fibers.