To define the physiologic pattern of regional intramural contractile function, 10 healthy volunteers (5 F, 5 M, 21-41 y) were studied with tagged cine MRI to assess systolic deformation (strain). Tagged images were acquired at 6 short axis (SA) levels. λ1, the maximum principal strain, (tissue lengthening) was oriented primarily in the radial direction. λ2, the minimum principal strain, (shortening) was oriented primarily in the circumferential direction. Strain measurements were performed in 4 cardiac segments (lateral, anterior, septal, and inferior walls) at each SA level (results from 2 of 6 SA levels in table). There was a general trend of decreasing λ1 and increasing λ2 from base to apex. λ2, was significantly different from base to apex only in the septum and inferior wall (p < 0.05) λ1, was different from base to apex in all 4 regions (p < 0.05). Within each SA slice, strain values were relatively uniform (diff. N.S.) across the 4 wall divisions. These data suggest that shortening is more uniform throughout the heart than is lengthening, and that deformation varies more from base to apex than within any SA slice. Therefore, substantial regional heterogeneity of function is present in normal hearts. Its measurement may permit regional assessment of intramural contractile dysfunction.