Background & Aims: Few data are available on risk of herpes zoster (HZ) infection in Asian patients with inflammatory bowel diseases (IBD). We investigated whether patients with IBD in Korea have an increased risk of HZ and sought to identify risk factors for infection. Methods: We performed a nationwide population-based study and a hospital-based, nested case–control study. Using the 2009–2013 data from the Korean national health insurance claims database, we calculated incidence rates and standardized incidence ratios (SIRs) of HZ infection in patients with IBD compared with the entire Korean population. In the nested case–control study, within a hospital-based cohort, 300 patients with IBD and HZ infection were matched with 895 patients with IBD without HZ. Results: In the nationwide population-based study, the incidence rate and SIR of HZ infection in patients with IBD were 18.34/1000 person-years and 1.48 (95% CI, 1.42–1.54), respectively. The SIR for HZ infection was higher in patients with Crohn's disease than in patients with ulcerative colitis (1.90 vs 1.36; P <.001) and higher in male patients than female patients (1.63 vs 1.33; P <.001). The incidence rate of HZ increased with age (P trend <.001), whereas the SIR of HZ infection decreased with age (P trend <.001). In the nested case–control study, corticosteroid use was associated with HZ infection (for ulcerative colitis, adjusted odds ratio, 2.44; 95% CI, 1.18–5.05 and for Crohn's disease, adjusted odds ratio, 2.70; 95% CI 1.25–5.83). Conclusions: In a population-based study in Korea, we found patients with IBD to have an increased risk for HZ infection—especially among patients who are male, younger, or have Crohn's disease. Corticosteroid use increases risk of HZ infection in patients with IBD.