There is limited information about mortality rates among patients with psoriasis and psoriatic arthritis (PsA) in North America and their change over the past two decades.To compare all-cause and cause-specific mortality rates in psoriatic patients to the general population in Ontario, Canada from 1996 to 2016.We conducted a population-based, retrospective cohort study of adult residents using administrative health data. All-cause and cause-specific standardized mortality rates, standardized mortality ratios and excess mortality rates were calculated.176,858 (2,524 deaths) psoriasis patients and 15,430 (221 deaths) PsA patients were identified in 2016. Patients with psoriasis and PsA had standardized excess mortality rates of 1.44 and 2.43 per 1000 population, respectively. Standardized mortality rates decreased by approximately 30% over the study period in both disease groups, but remained significantly elevated compared to the general population. The leading causes of death in psoriasis and PsA patients were cancer, circulatory disease and respiratory conditions.We were unable to classify patients according to disease severity.Despite improvements in psoriasis treatment, the relative excess mortality, which may be related to risk factors for psoriatic disease, remained unchanged, with an average of approximately 1-2 extra deaths per 1,000 patients in 2016.