This paper presents an algorithm that extracts accurate left ventricular (LV) boundaries from a two-dimensional (2-D) echocardiographic (echo) sequence covering a cardiac cycle. Unlike user-dependent, manual or semi-automatic techniques, the key feature of this algorithm is its truly automated processing for estimation. First, the algorithm performs smoothing of the image in the LV target area, followed by enhancement of intensity differences and edge detection. In order to best localize the position of the LV boundary, the algorithm uses a deformable template model derived from prior knowledge of LV shape and an edge map obtained from boundary estimation. The deformable template model is matched to the target by minimizing an energy function induced by the difference between edge locations and tangents of the template and those of the current frame edge map. Since the shape of the endocardial boundary will vary between temporally distinct frames, a controlled continuity spline, a "snake", is then used to implement refined active contour matching to the current frame LV boundary. Frame-to-frame tracking of the LV boundary is incorporated by using the boundary estimate from one frame to initialize and help with the estimation in the subsequent frame, which leads to faster and more accurate LV estimation throughout the image sequence. Test results of this algorithm show that the combination of approximate template matching with smoothness constraints in snakes produces good LV boundary extraction even with significant false and/or missing edge information caused by poor contrast and noise.