Embodiments for providing a color Doppler mode image are disclosed. In one embodiment, by way of non-limiting example, an ultrasound system comprises: an ultrasound data acquisition unit configured to transmit and receive ultrasound signals to and from a living body to acquire first ultrasound data and second ultrasound data; a user input unit configured to receive input information corresponding to a region of interest and a balance threshold value having a predetermined brightness value; and a processing unit configured to form a brightness mode image and a color Doppler mode image corresponding to the region of interest based on the first and second ultrasound data, respectively, form a balance mask for performing a balance process upon the color Doppler mode image based on the brightness mode image and the input information, and perform the balance process upon the color Doppler mode image based on the balance mask.