Many diseases result in a heterogeneous distribution of regional function. This results in the need for a technique that can accurately measure deformation with high spatial resolution. We have developed computer aided speckle interferometry (CASI) to accomplish this task. Instead of tracking individual particles, CASI tracks clusters of particles. In the isolated beating rabbit heart, CASI was used to determine the simultaneous displacement of 625 points located in a region approximately 5.5 × 5.5 mm. These displacements were plotted as a function of the left ventricular pressure to generate a regional work loop, which has conventionally been used to determine regional function in the myocardium. In summary, we have developed a technique to measure regional function with high spatial resolution and applied it to the beating heart.