Crohn's disease (CD) is an incurable chronic inflammatory disorder of the gastrointestinal tract. This study will assess how safe and effective upadacitinib is in treating moderately to severely active CD in real world. Adverse events and change in disease activity will be assessed.

Upadacitinib is a drug approved for the treatment of CD. All study participants will receive upadacitinib as prescribed by their study doctor in accordance with approved local label. Approximately 240 participants will be enrolled in Japan.

Participants will receive upadacitinib as prescribed by their physician according to their routine clinical practice and local label. Participants will be followed for up to 64 weeks.

There is expected to be no additional burden for participants in this trial. Study visits may be conducted on-site or virtually as per standard of care.

Inclusion Criteria:

• Diagnosed with moderately to severely active Crohn's disease (CD).
• Has been prescribed upadacitinib for CD as per most current local approved label after its approval for CD in Japan.
• Within 14 days from the commencement of upadacitinib induction treatment for CD at the participating institution.

Exclusion Criteria:

• Currently participating in another interventional clinical research.
• Participants for whom upadacitinib is contraindicated.
• Has been treated with upadacitinib for CD before and continue treatment with upadacitinib for CD at the participation to this study.

Children and Adult participants with Crohn's disease (CD) in Japan.