This is a US multi-center, prospective, real world, observational drug registry enrolling patients actively treated with Uptravi. Participating patients will be followed prospectively for a maximum of 18 months from the date of enrollment into the registry.

Inclusion Criteria:

• Signed patient informed consent form (ICF).

• Patients ≥ 18 years of age at time of Uptravi initiation, and

• Patients who initiate Uptravi:

  • at enrollment, or
  • less than or equal to 60 days prior to enrollment and have a documented titration regimen (defined as all documented dose changes including, but not limited to: starting dose and dates and highest tolerated dose and dates)

Exclusion Criteria:

• Patients previously exposed to Uptravi treatment during a clinical trial.
• Patients that previously discontinued Uptravi for any reason, prior to study enrollment (discontinuation defined as an interruption of therapy greater than or equal to 30 days).
• Patients enrolled in a blinded clinical trial or in a clinical trial involving an unapproved drug.

The number of patients planned to be enrolled in the study is approximately 800 patients from approximately 80 centers in the U.S.