Inclusion Criteria:

• Clinical diagnosis of axSpA upon physician's judgement.
• Physician decision on participant treatment with upadacitinib must have been reached prior to and independently of recruitment in the study.
• Upadacitinib prescribed in accordance with the local label.

Exclusion Criteria:

• Prior exposure to any Janus kinase (JAK) inhibitor (including but not limited to upadacitinib, tofacitinib, baricitinib, and filgotinib).
• Participants with primary fibromyalgia (upon physician´s judgement)
• Participation in a clinical trial of an investigational drug, concurrently or within the last 30 days or five half-lives of the drug (whichever is longer) prior to the first dose of study drug or is currently enrolled in another clinical study.
• Participants who cannot be treated with upadacitinib according to the applicable local label.