The real-time display of full-range, $2048\text{\hspace{0.17em} axial pixel}\times 1024\text{\hspace{0.17em} lateral pixel}$ , Fourier-domain optical- coherence tomography (FD-OCT) images is demonstrated. The required speed was achieved by using dual graphic processing units (GPUs) with many stream processors to realize highly parallel processing. We used a zero-filling technique, including a forward Fourier transform, a zero padding to increase the axial data-array size to 8192, an inverse-Fourier transform back to the spectral domain, a linear interpolation from wavelength to wavenumber, a lateral Hilbert transform to obtain the complex spectrum, a Fourier transform to obtain the axial profiles, and a log scaling. The data-transfer time of the frame grabber was $15.73\mathrm{ms}$ , and the processing time, which includes the data transfer between the GPU memory and the host computer, was $14.75\mathrm{ms}$ , for a total time shorter than the $36.70\mathrm{ms}$ frame-interval time using a line-scan CCD camera operated at $27.9\mathrm{kHz}$ . That is, our OCT system achieved a processed-image display rate of 27.23 frames/s.