The high prevalence of psoriasis and the high spending on pharmaceuticals motivate a more evidence-based and cost-effective usage of biopharmaceuticals. A growing body of evidence exists that the implementation of therapeutic drug monitoring for biopharmaceuticals in psoriasis patients optimizes patient management and clinical outcome and enhances their efficacy. Therefore, the aim of this review was to give an overview of the literature on therapeutic drug monitoring of biopharmaceuticals in the treatment of psoriasis and to provide the useful information to dermatologists to improve health care in psoriasis patients.