We demonstrate 3-D optical coherence tomography using only 1-D mechanical scanning. This system uses the principle of Fourier domain optical coherence tomography for depth resolution, 1-D imaging for lateral vertical resolution, and mechanical scanning by a galvanometer for lateral horizontal resolution. An in vivo human fingerpad is investigated in three dimensions with an image size of 480 points (vertical) 300 points (horizontal) 1024 points (depth), which corresponds to . The acquisition time for a single cross section is and that for a single volume is . The system sensitivity is at a probe beam power of .