This is a retrospective, multi-center observational cohort study. This study will be implemented first in Germany (approximately 50 sites), the United Kingdom (approximately 20 sites) and Sweden (approximately 25 sites), followed by a selected number of countries in Europe, depending on apremilast local availability. The design of this apremilast retrospective study aims to provide clinical information regarding the treatment initiation and outcomes in psoriasis patients when prescribed apremilast in real world settings. In addition, this study is aiming at capturing physicians' and patients' treatment goals when initiating apremilast and whether these goals are achieved following apremilast use. This study is primarily descriptive in nature, and no a priori hypotheses are specified. Patients must voluntarily sign an informed consent form, be 18 or over, have been diagnosed with plaque psoriasis and have been treated with apremilast during the previous 5-7 months to participate in this study. They must not be involved in any other clinical study involving apremilast.