Mild cognitive impairment (MCI) is an intermediate cognitive state between normal aging and dementia. Previous studies have found the atrophy of the gray matter and white matter in MCI compared to normal aging. However, the relatively few reports focused on the sulcal morphology in MCI subjects. Here, we investigated the changes of sulcal morphology in MCI and normal controls using quantitative surface-based method. We computed three dimensional gyrification indexes (3D-GI) of both cerebral hemispheres and four morphological metrics (the bottom length, top length, average depth and maximum depth) in nine prominent sulci per hemisphere, as well as the asymmetry index (AI) of these metrics. The relationships among those metrics and Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA) scores in MCI patients were also investigated. We found that 3D-GI was not significantly different between MCI subjects and normal controls. Interestingly, we observed that the lengths and depths of the left superior and inferior frontal sulci in MCI subjects showed significant differences compared to the normal people. And the AI differences existed in the superior frontal, inferior frontal, and post-central, intra-parietal sulci. Taken together, our results showed sulcal morphology changes in MCI patients and therefore provided insights into the cognitive decline process. © 2011 IEEE.