Objectives：The purpose of this study is to determine whether Rhus verniciflua Stokes with Latin name Lacca Sinica Exsiccata, and Eucommia ulmoides Oliver with Latin name Eucommiae Cortex Extract Combination (ILF-RE) improves laboratory test results in participants with liver function disorder. Methods：This study was conducted at Woosuk university Korean medicine hospital where participants with high serum alanine transaminase (ALT) levels from 45 to 135 U/L were enrolled. Subjects received ILF-RE 3.6 g (1.2 g/day as ILF-RE) or placebo 3.6 g for 12 weeks. It was confirmed that urushiol was not detected in ILF-RE. The primary outcomes were the decrement degree of serum ALT and gamma-glutamyl transferase (GGT) levels between two groups. The secondary outcomes were the decrement degree of serum aspartate transaminase (AST), alkaline phosphatase (ALP), lactate dehydrogenase (LD), total bilirubin, total cholesterol, triglyceride (TG) and fatty liver index (FLI) levels between two groups. Adverse events, skin prick tests, laboratory tests, and vital signs were observed and analyzed to confirm the safety of ILF-RE.1) Results：In the ILF-RE group, the liver function index ALT, GGT, lipid metabolism index TG, and fatty liver index FLI were significantly decreased compared to the placebo group. There was no significant difference in ILF-RE group in terms of adverse events, severe adverse events, skin prick test, laboratory test, and vital signs compared with placebo group. Conclusions：ILF-RE was found to be effective in improving liver function. In addition, no clinically significant adverse events or body changes were observed during this study.