Ultrasound, in the frequency range of 1-20 MHz, is extensively used for medical imaging. Ultrasonography relies on reflection of ultrasound waves from the object. Thus, an ultrasound image represents the properties of the object (biological tissues) at ultrasound frequencies. Although ultrasound imaging has been proven useful in many clinical applications, it is also of interest to obtain images that represent the low-frequency characteristics of the tissue because such images can reveal different characteristics of the object. This paper investigates an imaging method that is based on the response of tissue to a low-frequency vibration. This method uses the radiation force of focused ultrasound to generate a low-frequency stress field inside tissue. Acoustic response of the object is recorded for each point of the object to form an image representing the low-frequency characteristics of the object. The purpose of this paper is to investigate the characteristics of the low-frequency image and compare them to those of the high-frequency (ultrasound) image for various types of biological tissues. Experimental results obtained from a series of human tissues, including breast, prostate, and thyroids are provided and clinical significance of each image is discussed. Also, efficacy of images in revealing clinically relevant information is evaluated and contrasted. It is concluded that these two imaging methods can reveal different features of tissue, thus using both modalities can provide complementary information for clinical evaluation of tissue.