Background & Aims: Despite the emergence of mucosal healing (MH) as a major therapeutic goal in Crohn’s disease (CD), its feasibility into real-life practice is limited, especially in the pediatric population. We aimed to investigate whether fecal calprotectin (FC) may serve as a surrogate marker of predicting MH in pediatric CD patients under sustained clinical remission with biologics. Methods: This study was a retrospective observational study conducted at the Department of Pediatrics of two tertiary hospitals in Korea. Patients included in the study were (1) pediatric CD patients diagnosed before the age of 19, (2) under sustained clinical remission for at least 6 months with biologics, and (3) had simultaneously performed ileocolonoscopies and FC as well as other laboratory tests. The correlation between the Simple Endoscopic Score for Crohn’s disease (SES-CD) and FC levels, as well as the association between MH and FC were investigated. Furthermore, the optimal cut-off level of FC in predicting MH was derived. Complete MH was defined as SES=0, and partial MH was defined as SES-CD3. Results: A total 99 patients (65 males, and 34 females) were included in this study. FC levels were significantly higher in patients who had achieved complete MH (median 34.1 vs. 514.3 μg/g, P0.001), and also who had achieved partial MH (median 38.5 vs. 710.5 μg/g, P0.001), respectively. SES-CD scores and FC levels showed a significant correlation ( Pearson ρ=0.71, P0.001). According to logistic regression analysis, FC (*10sup＞-2/sup＞) was the only factor associated with both complete MH (OR=0.47, 95% CI 0.31-0.63, P0.001), and partial MH (OR=0.62, 95% CI 0.5-0.73, P0.001), respectively. According to receiver operating curve analysis, the optimal cut-off level of FC in predicting complete MH and partial MH was 97.9 (AUC=0.907, 95% CI 0.844-0.969, sensitivity 88.2%, specificity 87.5%, PPV 87.5%, NPV 88.2%, P0.001) and 122.4 (AUC=0.904, 95% CI 0.842-0.967, sensitivity 79.7%, specificity 94.3%, PPV 71.7%, NPV 96.2%, P0.001), respectively. Conclusions: FC is capable of predicting mucosal healing in pediatric CD patients under sustained clinical remission with biologics. Development of a composite scoring system incorporating FC may diminish the need for ileocolonoscopies in patients under sustained clinical remission with biologics.