Background & aims Liver fibrosis is the critical determinant of liver-related outcomes in persons with nonalcoholic fatty liver disease. The rate that fibrosis develops determines the time taken to reach cirrhosis and consequent clinical outcomes. Estimates of the fibrosis progression rate (FPR) are uncertain having been defined in small observational series that rely largely on nonstandardised repeat biopsy in selected patients. The aim of this study was to evaluate the FPR in placebo-treated participants with nonalcoholic steatohepatitis (NASH) in randomised controlled trials (RCTs). Methods Systematic review and meta-analysis of RCTs in NASH with data on fibrosis change extracted. Calculated fibrosis progression rates were pooled in meta-analysis. The pooled estimate was then used to model the proportion of hypothetical cohorts starting with no fibrosis at the age of 30 who develop cirrhosis. Results A total of 35 trials including 1419 placebo-treated participants who underwent repeat liver biopsy were evaluated. Considering all trials, the overall FPR was 0.00 stages per year, increasing to 0.03 stages per year in both trials at low risk of bias and trials including >50 placebo-treated participants. This estimate was markedly lower than the value derived from previously pooled analyses of observational data. Using a FPR of 0.03 resulted in a substantial reduction in the proportion of patients developing cirrhosis compared with the FPR derived from observational studies (13% vs 28%). Conclusions The FPR in placebo-treated participants in RCTs is lower than that described from observational data. Slower fibrosis progression predicts fewer persons with NASH will progress to cirrhosis than previously estimated.