Little reliable evidence has been reported regarding usefulness of liver stiffness measurement (LSM) for monitoring the hepatic fibrosis changes during treatment. We aimed to assess the association between changes in LSM and histological outcomes in patients with chronic hepatitis B. In this prospective multicenter study, 727 treatment-naive patients receiving entecavir-based therapy, who underwent paired biopsies at treatment baseline and week 72, were analyzed. Changes in LSM were defined as ≥30% decrease, minor change, and ≥30% increase. Multivariate logistic regression was used to estimate odds ratios (ORs) of changes in LSM on clinical outcomes accounting for regression to the mean. A new on-treatment LSM threshold was established by receiver operating curve. Overall regression of fibrosis, improvement of inflammation, significant histological response, virologic response, alanine aminotransferase normalization, and hepatitis B e antigen seroconversion were 51.2%, 74.4%, 22.0%, 86.0%, 83.5%, and 13.3%, respectively. The association between changes in LSM and improvement of inflammation was nonlinear (P = 0.012). LSM decrease ≥30% was associated with regression of fibrosis (OR 1.501, 95% confidence interval [CI] 1.073-2.099, P = 0.018), significant histological response (OR 1.726, 95% CI 1.124-2.652, P = 0.013), and alanine aminotransferase normalization (OR 2.149, 95% CI 1.229-3.757, P = 0.007). After adjusting for regression to the mean, LSM increase ≥30% became negatively associated with the above 3 outcomes. A new on-treatment LSM cutoff value of 5.4 kPa was established for indicating the significant histological response. Changes in LSM are unreliable to estimate regression of fibrosis during treatment; the established cutoff value of on-treatment LSM can optimize monitoring strategy for histological outcomes in patients with chronic hepatitis B. Copyright © The American College of Gastroenterology 2021. All Rights Reserved.