Background/Objectives: Increasing evidence suggests that altered methionine/folate metabolism may contribute to the development of hepatic injury. We addressed the question of whether folic acid (FA) supplementation can affect serum alanine aminotransferase (ALT) level in hypertensive Chinese adults. Subjects/Methods: A total of 480 participants with mild or moderate essential hypertension and without known hepatic disease were randomly assigned to three treatment groups: (1) enalapril only (10 mg, control group); (2) enalapril-FA tablet (10 mg enalapril combined with 0.4 mg of FA, low FA group); and (3) enalapril-FA tablet (10 mg enalapril combined with 0.8 mg of FA, high FA group), once daily for 8 weeks. Results: This report included 455 participants in the final analysis according to the principle of intention to treat. We found a significant reduction in ALT level in the high FA group (median (25th percentile, 75th percentile), -0.6 (-6.9, 2.0) IU/l, P=0.0008). Compared with the control group, the high FA group showed a significantly greater ALT-lowering response in men (median ALT ratio (ALT at week 8 to ALT at baseline; 25th percentile, 75th percentile): 0.93 (0.67, 1.06) vs 1.00 (0.91, 1.21), P=0.032), and in participants with elevated ALT (ALT>40 IU/l) at baseline. There was no difference in ALT lowering between the control and the low FA group. Conclusions: Compared with treatment using 10 mg of enalapril alone, a daily dose of 10 mg enalapril combined with 0.8 mg of FA showed a beneficial effect on serum ALT level, particularly in men and in participants with elevated (440 IU/l) ALT. European Journal of Clinical Nutrition (2012) 66, 541-548; doi: 10.1038/ejcn.2011.192; published online 16 November 2011