Color Doppler optical coherence tomography (CDOCT) is a functional extension of optical coherence tomography that can image flow in turbid media. We have developed a CDOCT system capable of imaging flow in real time. Doppler processing of the analog signal is accomplished in hardware in the time domain using a novel autocorrelation technique. This Doppler processing method was implemented on a high speed OCT system employing a rapid scanning optical delay line in the reference arm of the interferometer. Image data was acquired, processed, and displayed in real time. We have demonstrated, for the first time, imaging of bi-directional flow with CDOCT in real time in a tissue-simulating phantom consisting of intralipid solution flowing in glass capillaries submerged in intralipid solution. Issues of velocity resolution, imaging speed, and range of velocity measurement are discussed, as well as potential applications of real-time CDOCT.