B-flow imaging is a recently developed ultrasound technique that extends the B-mode imaging quality of blood flow, including high-frame-rate and high-spatial-resolution imaging. The purpose of the present study was to clarify the usefulness of B-flow for evaluation of the hemodynamics of superficial soft tissue tumors. All 33 cases of superficial soft tissue tumors were examined by both B-flow and Color/Power Doppler methods on the same plane. The B-flow images that were obtained were evaluated by comparison with corresponding Color/Power Doppler images. The following four items were compared and evaluated: (1) sensitivity to the detection of tumor vessels; (2) quality of background B-mode imaging; (3) frame rate; and (4) spatial resolution of tumor vessels. B-flow was somewhat inferior to Color/Power Doppler imaging in sensitivity to the detection of tumor vessels. B-flow was clearly inferior in the quality of background B-mode imaging. B-flow provided high-frame-rate imaging. The diameter of tumor vessels on B-flow imaging was clearly thinner than that on Color/Power Doppler images and appeared to indicate the true diameter of tumor vessels. By providing high-frame-rate imaging and high spatial resolution, B-flow makes it possible to clarify the precise vascular structure.