The initial results from an ongoing clinical study investigating the utility of Acoustic Radiation Force Impulse (ARFI) imaging for in vivo visualization of abdominal lesions are presented. To date, 13 patients with lesions located in the liver (n = 11) or kidney (n = 2) have been included. Preliminary results establish the feasibility of visualizing both primary and secondary liver tumors and primary renal cell tumors with ARFI imaging. For every lesion encountered to date, displacement contrast in ARFI images has exceeded echo contrast in B-mode ultrasound images. In general, boundary definition of lesions in ARFI images is superior to that seen with sonography. © 2007 IEEE.