Interleukin (IL)-22 plays a prominent role in the regulation of epithelial barrier integrity and the promotion of tissue repair. RORγt+group 3 innate lymphoid cells (ILC3s) are known as a major source of IL-22 in the intestinal mucosa. Given the importance of IL-22 in the mucosal barrier, ILC3 plays a critical role in the maintenance of the homeostasis in the intestine. However, little is known about the extent to which the function of ILC3s is impaired in patients with inflammatory bowel disease (IBD).