Embodiments for performing an image process and a size measurement upon a three-dimensional ultrasound image are disclosed. In one embodiment, by way of non-limiting example, an ultrasound system comprises: a user input unit configured to receive input information for setting at least one seed point on a two-dimensional ultrasound image from a user an ultrasound data acquisition unit configured to transmit and receive ultrasound signals to and from a target object including a plurality of objects of interest and output ultrasound data and a processing unit configured to form volume data based on the ultrasound data, form the two-dimensional ultrasound image and a three-dimensional ultrasound image based on volume data, detect at least one object of interest corresponding to the input information from the three-dimensional ultrasound image, and perform an image process and a size measurement of the detected object of interest upon the three-dimensional ultrasound image.
