This is a multi-centre, non-interventional, open-label, prospective observational study that will be conducted across Canada over 52-week duration. Approximately 80 patients who are initiating tildrakizumab as part of their routine care through the ILUMYA SUPPORT® Program and meet the study's eligibility criteria will be enrolled. Specifically, the study will enroll patients with Fitzpatrick scale skin types III and above.

The real-world impact, safety and effectiveness of tildrakizumab on patients with moderate-to-severe plaque psoriasis (PsO) remain largely undocumented in Canada, despite its approval in 2018. Given Canada's diverse population, this study presents an opportunity to evaluate tildrakizumab's quality of life, safety and effectiveness in specific demographic groups, particularly those patients with Fitzpatrick scale skin type III and above.

The findings from this study will help optimize care, address unmet needs, and ensure that treatment outcomes are inclusive and reflective of Canada's diverse population.

Inclusion Criteria:

1. Adults aged 18 years or older.

2. Diagnosis of moderate-to-severe chronic plaque-type PsO with Fitzpatrick scale type III or above (BSA >/=3%).

3. Candidate for phototherapy and/or systemic therapy.

4. Planning to initiate tildrakizumab as part of routine clinical care through the ILUMYA SUPPORT® Program for the treatment of plaque PsO but has not yet received their first dose.

   a. Decision to treat with tildrakizumab must be made independently of and prior to study recruitment.

5. Must be able to read, understand, and communicate in English.

6. Must be willing to participate in the study and capable to provide informed consent

7. Able to comply with all study procedures and attend all study visits

Exclusion Criteria:

1. Known hypersensitivity to tildrakizumab, its excipients, or components of the container, as outlined in the Product Monograph.
2. Concurrently taking any oral medication for treatment of PsO (e.g. methotrexate, cyclosporin, acitretin)
3. Diagnosis of only palmoplantar psoriasis
4. Concurrent medical condition or significant comorbidities that, in the investigator's opinion, would prevent participation in the study or interfere with study assessments
5. Women of childbearing potential who are pregnant, planning to become pregnant, or breastfeeding.
6. Prior (within 30 days) or actively participating in other interventional clinical trial(s).
7. Unable or unwilling to comply with study procedures including completing questionnaire.
8. Any other condition that, in the opinion of the investigator, could create a hazard to the participant's safety, endanger the study procedures, or interfere with the interpretation of study results

Patients with moderate-to-severe psoriasis (PsO) planning to initiate treatment with tildrakizumab and meet Fitzpatrick scale skin type III or above.

Patients that are either naïve to PsO treatment with a biologic or those who have previously been exposed to a biologic PsO treatment will be eligible for the study.