Assessment of segmental wall motion is one of the most challenging tasks in echocardiography. One major limitation is impairment of echocardiographic regional wall motion by incomplete endocardial definition. The newly developed tissue harmonic imaging method may improve the detection of left ventricular endocardial border. This study examined the impact of native tissue harmonic imaging on endocardial border definition. Fundamental and harmonic imaging were compared for detecting the endocardial border in 96 segments of 16 patients (age 54 +/- 8 years). Visualization of endocardial border was better with harmonic imaging than with fundamental mode in 49% (47 of 96 segments). Thus, tissue harmonic imaging has a significant impact on endocardial border definition.