Objectives: To examine the effect of long-term Korean medicine treatment on mild cognitive impairment (MCI). Methods: This study was conducted on two patients who were diagnosed with mild cognitive impairment and received long-term Korean medicine treatment. In order to evaluate the degree of cognitive decline, SNSB and K-MMSE were performed 2∼3 times at the first visit and during the treatment process. Results: Both cases 1 and 2 were diagnosed with MCI with a high possibility of developing dementia. In case 1, MCI progressed to early dementia at one year after the diagnosis of MCI. However, in case 2, that MCI status was maintained without progressing to dementia for 4 years after the diagnosis of MCI. The cause of such difference in the course of MCI might be attributed to the fact that Case 1 had lower K-IADL level but higher SGDS level than Case 2 at the time of initial diagnosis, with weak family support and irregular herbal medicine intake. Conclusions: Korean medicine treatment could improve and manage symptoms of cognitive decline due to MCI.