Colorectal adenoma is benign glandular tumor of colon, the precursor of colorectal cancer. But no pharmaceutical medication is currently available to treat and prevent adenomas.To evaluate efficacy of Shenbai Granules, an herbal medicine formula, in reducing the recurrence of adenomas.This multicenter, randomized, double-blind, placebo-controlled clinical trial was conducted by eight hospitals in China.Patients who had received complete polypectomy and were diagnosed with adenomas within the recent 6 months were randomly assigned (1:1) to receive either Shenbai granules or placebo twice a day for 6 months. An annual colonoscopy was performed during the 2-year follow-up period. The primary outcome was the proportion of patients with at least one adenoma detected in the modified intention-to-treat (mITT) population during follow-up for 2 years. The secondary outcomes were the proportion of patients with sessile serrated lesions and other specified polypoid lesions. The data were analyzed using logistic regression.Among 400 randomized patients, 336 were included in the mITT population. We found significant differences between treatment and placebo groups in the proportion of patients with at least one recurrent adenoma (42.5 % vs. 58.6 %; OR, 0.47; 95 % CI, 0.29-0.74; p = 0.001) and sessile serrated lesion (1.8 % vs. 8.3 %; OR, 0.20; 95 % CI, 0.06-0.72; p = 0.01). There was no significant difference in the proportion of patients developing polypoid lesions (70.7 % vs. 77.5 %; OR, 1.43; 95 % CI, 0.88-2.34; p = 0.15) or high-risk adenomas (9.0 % vs. 13.6 %; OR, 0.63; 95 % CI, 0.32-1.25; p = 0.18).Shenbai Granules significantly reduced the recurrence of adenomas, indicating that they could be an effective option for adenomas. Future studies should investigate its effects in larger patient populations and explore its mechanism of action to provide more comprehensive evidence for the use of Shenbai Granules in adenoma treatment.Copyright © 2024 The Author(s). Published by Elsevier GmbH.. All rights reserved.