Background and Aim: Mild cognitive impairment (MCI) is characterized by declined cognitive function greater than that expected for a person’s age. The clinical significance of this condition is its possible progression to dementia. MLC601 is a natural neuroprotective medication that has shown promising effects in Alzheimer disease. Accordingly, we conducted this randomized, double-blind, placebo-controlled study to evaluate the efficacy and safety of MLC601 in MCI patients. Methods: Seventy-two patients with a diagnosis of MCI were recruited. The included participants were randomly assigned to groups to receive either MLC601 or placebo. An evaluation of global cognitive function was performed at baseline as well as at 3-month and 6-month follow-up visits. Global cognitive function was assessed by Mini-Mental State Examination (MMSE) and Alzheimer’s Disease Assessment Scale-cognitive subscale (ADAS-cog) scores. Efficacy was evaluated by comparing global function scores between the 2 groups during the study period. Safety assessment included adverse events (AEs) and abnormal laboratory results. Results: Seventy patients completed the study, 34 in the MLC601 group and 36 in the placebo group. The mean changes (±SD) in cognition scores over 6 months in the MLC601 group were –2.26 (±3.42) for the MMSE and 3.82 (±6.16) for the ADAS-cog; in the placebo group, they were –2.66 (±3.43) for the MMSE and 4.41 (±6.66) for the ADAS-cog. The cognition changes based on both MMSE and ADAS-cog scores were statistically significant between the placebo and the MLC601 group (p < 0.001). Only 5 patients (14.7%) reported minor AEs in the MLC601 group, the most commonly reported of which were gastrointestinal, none of them leading to patient withdrawal. Conclusion: MLC601 has shown promising efficacy and acceptable AEs in MCI patients.