There is little consensus on the optimal timing of anti-tumor necrosis factor (anti-TNF) therapy to decrease the rates of hospitalization and surgery in Crohn disease (CD). We aimed to assess the real-world outcomes of anti-TNF therapy and estimate the optimal timing of anti-TNF therapy in Korean patients with CD.Claims data were extracted from the Korean Health Insurance Review and Assessment Service database. Incident patients diagnosed with CD between 2009 and 2016, with at least 1 anti-TNF drug prescription, and with follow-up duration > 6 months were stratified according to the number of relapses prior to initiation of anti-TNF therapy: groups A (≤1 relapse), B (2 relapses), C (3 relapses), and D (≥4 relapses). The cumulative survival curves free from emergency hospitalization (EH) and surgery were compared across groups.Among the 2173 patients analyzed, the best and worst prognoses were noted in groups A and D, respectively. The incidences of EH and surgery decreased significantly as the use of anti-TNF agents increased. The 5-year rate of hospitalization was significantly lower in group A than in groups C and D (P = .004 and .020, respectively), but similar between groups A and B. The 5-year rate of surgery was lower in group A than in group C (P = .024), but similar among groups A, B, and D.In Asian patients with CD, anti-TNF therapy reduces the risk of EH and surgery and should be considered before three relapses, regardless of disease duration.