Judgements on the effectiveness of psoriasis management are based on clinical criteria employed by dermatologists, and how they take account of patients’ experiences in the process of history taking. In this study the aim was to gain the in-depth patients’ perspective and investigate the criteria that they employ when making judgements about the effectiveness of their therapy. These findings were then compared with the clinical and research literature on the clinical effectiveness of psoriasis treatments. The study design is exploratory-descriptive, using a qualitative ethnographic approach. In-depth interviews were undertaken in an outpatient department dermatology clinic. A purposive sample of 20 adult patients currently attending represented the following types of psoriasis: guttate, chronic plaque and scalp. A key comparable finding between the literature and the interview data is that dermatologists emphasize observable criteria of effectiveness, such as clearance of the lesion, whereas patients emphasis focuses on the subjective concerns, such as suppleness, softness and alleviation of itch. This discrepancy needs to be considered during history taking, in relation to its impact on therapy concordance and in the use and development of outcome measures used for clinical assessment and evaluations of psoriasis therapy.