The aim of the present study was to explore the value of baseline serum exosomal miR-155-5p expression level combined with HBV DNA quantification in predicting HBeAg seroconversion in chronic hepatitis B (CHB) patients treated with peginterferon (Peg-IFN) for 48 weeks. A total of 88 HBeAg-positive CHB patients who initially received Peg-IFN therapy in our hospital from June 2016 to June 2019 were retrospectively analyzed. Patients were divided into treatment response and non-response group according to HBeAg seroconversion after Peg-IFN treatment for 48 weeks. Multivariate logistic regression analysis was performed to identify predictors of treatment response, and the area under receiver operating characteristic (ROC) curve was used to evaluate the predictive efficacy. The results indicated that baseline serum exosomal miR-155-5p [odds ratio (OR) ＝2.193, 95% confidence interval (CI) 1.315～3.655, P＝0.003] and HBV DNA (OR＝0.398, 95% CI 0.163～0.976, P＝0.036) were independent predictors for HBeAg seroconversion. The optimal cut-off value of baseline serum exosomal miR-155-5p and HBV DNA were 2.3 and 7.2 log₁₀IU/mL, respectively; and the corresponding area under ROC curves were 0.788 (95% CI 0.682～0.893) and 0.704 (95% CI 0.577～0.824), respectively. Patients with baseline serum exosomal miR-155-5p expression level ≥2.3 and HBV DNA ≤7.2 log₁₀IU/mL had 66.67% (10/15) rates of HBeAg seroconversion, whereas the rates of HBeAg seroconversion among patients with unfavorable baseline characteristics were only 3.03% (1/33). Taken together, these results suggest that baseline serum exosomal miR-155-5p combined with HBV DNA quantification may serve as a useful predictor of Peg-IFN therapy efficacy in HBeAg-positive CHB patients.