The present disclosure is directed to methods for treating Crohn's disease, and in particular, to methods for inducing clinical remission and/or endoscopic improvement of Crohn's disease, using a JAK1 inhibitor. In certain embodiments, the patient is administered an induction dose of the JAK1 inhibitor to induce clinical remission and/or endoscopic improvement of the Crohn's disease, followed by administration of at least one maintenance dose of the JAK1 inhibitor thereafter. In other embodiments, the present disclosure is directed to methods for treating ulcerative colitis using a JAK1 inhibitor.