Background/Aims: Although anti-tumor necrosis factor (TNF)-α agents are important therapeutic drugs for Crohn’s disease (CD), data regarding their long-term sustained effects are limited. Herein, we evaluated the long-term loss of response (LOR) to anti-TNF-α agents in patients with CD. Methods: This retrospective study included patients with CD who started treatment with infliximab or adalimumab as a first-line therapeutic approach. The cumulative event-free, retention, and surgery-free rates after the start of biological therapy were analyzed. Secondary LOR was analyzed in patients who achieved corticosteroid-free clinical remission after the start of biological therapy. Cox proportional hazards models were used to analyze the predictive factors of secondary LOR. Results: The cumulative event-free rates at 1, 2, 5, and 10 years were 83.3%, 75.1%, 37.4%, and 23.3%, respectively. The incidence of LOR was 10.6% per patient-year of follow-up. At 12–14 weeks after the start of biological therapy, the proportion of patients with a C-reactive protein to albumin (CRP/ALB) ratio ≥0.18 was significantly higher in patients with LOR (P<0.001). Multivariate analysis indicates that a CRP/ALB ratio ≥0.18 (hazard ratio [HR], 5.86; 95% confidence interval [CI], 1.56–22.0; P=0.009) and upper gastrointestinal tract inflammation (HR, 3.00; 95% CI, 1.26–7.13; P=0.013) were predictive factors of secondary LOR. Conclusions Although anti-TNF-α agents contributed to long-term clinical remission of CD, the annual incidence of secondary LOR was 10.6%. The CRP/ALB ratio at 3 months after the start of biological therapy and upper gastrointestinal tract inflammation were identified as predictive factors of secondary LOR.