Relationships between the capsule endoscopy Lewis score (LS) and clinical disease activity indices and C-reactive protein (CRP) are controversial in adult patients with Crohn's disease (CD). Also, data on pediatric patients are relatively less. However, correlation between LS and small bowel transit time (SBTT) remains investigational. The aim of the present study was to explore the correlations between LS and clinical disease activity indices, CRP, SBTT in pediatric, and adult patients with small bowel CD.Retrospective, single-center study on consecutive inpatients with established small bowel CD was conducted. The clinical disease activity index was determined using the abbreviated Pediatric Crohn's Disease Activity Index (aPCDAI) in patients aged <18 years and the Harvey-Bradshaw Simple Index (HBI) in adults. Spearman's rank correlation coefficient was used to assess the correlations of LS with aPCDAI, HBI, CRP, and SBTT, respectively.150 patients were enrolled (30 children and adolescents). In pediatric patients, correlations between LS and aPCDAI, CRP were moderate (r1 = 0.413; r2 = 0.379; P1 = .023; P2 = .044). There was no correlation between LS and SBTT (r = -0.029; P = .88). In adults, weak correlations were found between LS and HBI, SBTT (r1 = 0.213; r2 = 0.237; P1 = .019; P2 = .009). Correlation between LS and CRP was moderate (r = 0.326; P < .001). Strong correlations were found between CRP and HBI, aPCDAI (r1 = 0.522; r2 = 0.650; P < .001). The follow-up patients were all in clinical remission after treatment within 4 months, whereas only a minority reached mucosal healing. HBI, aPCDAI, CRP, and LS in all patients were reduced after treatment, whereas difference in CRP in pediatric patients and difference in LS in adults between baseline and follow-up were not found to be statistically significant. Also, the average SBTT at baseline was not found to be different from that at follow-up in all patients.The role of capsule endoscopy should be emphasized both in pediatric and adult patients with small bowel CD. Furthermore, the small bowel transit time may not be affected by the grade of small intestinal inflammation.