Noninvasive tests for the assessment of liver fibrosis are highly needed for the management of patients with autoimmune hepatitis (AIH). We aimed to investigate the accuracy of red cell distribution width to platelet ratio (RPR) in predicting liver fibrosis in AIH patients. One hundred nineteen AIH patients who underwent liver biopsy were enrolled. Liver fibrosis stage was diagnosed using the Scheuer scoring system. The diagnostic accuracy was evaluated by the area under the receiver operating characteristic curve (AUROC). RPR values in AIH patients with S2-S4 (0.10, interquartile range [IQR] 0.08-0.15), S3-S4 (0.10, IQR 0.09-0.14), and S4 (0.14, IQR 0.09-0.19) were significantly higher than patients with S0-S1 (0.07, IQR 0.06-0.08, P < .001), S0-S2 (0.08, IQR 0.06-0.12, P = .025) and S0-S3 (0.09, IQR 0.07-0.13, P = .014), respectively. The RPR was positively correlated with fibrosis stages (r = 0.412, P < .001), while aspartate transaminase to platelet ratio index (APRI) and fibrosis-4 score (FIB-4) were not significantly associated with fibrosis stages in AIH patients. The AUROCs of RPR in identifying significant fibrosis (S2-S4), advanced fibrosis (S3-S4), and cirrhosis (S4) were 0.780 (95% confidence interval [CI] 0.696-0.865), 0.639 (95% CI 0.530-0.748), and 0.724 (95% CI 0.570-0.878), respectively. The AUROCs of RPR were significantly higher than APRI and FIB-4 in diagnosing significant fibrosis, advanced fibrosis, and cirrhosis. Our study demonstrates that the RPR is a simple predictor of liver fibrosis and is superior to APRI and FIB-4 in identifying liver fibrosis in AIH patients.