OBJECTIVES: Psoriasis vulgaris is one of the most frequent chronic diseases in dermatology and can cause a high disease burden and reduction of quality of life. The severity of psoriasis is determined by the clinical parameter PASI (Psoriasis Area and Severity Index). It is the most often cited measurement to determine the efficacy of therapies. Since the assessment of patient relevant treatment benefit gains importance in treatment evaluation, the objective of the study was to test to what extent PASI improvements agree with patient relevant benefit parameter. METHODS: A multicenter longitudinal observational study was conducted in n = 218 patients with psoriasis vulgaris. Data collection took place at the beginning of psoriasis treatment and between three and eight weeks after treatment. In addition to PASI, physician and patient data were collected, e.g. socio-demographics, clinical features, dermatological quality of life (DLQI), and assessment of treatment. RESULTS: Each level of PASI (50, 75, 90) showed relevant improvements in patient reported outcomes. The satisfaction with the treatment and the patient benefit was greater, the higher PASI was reached. This effect was not seen for DLQI. However, improvements were only significant for PBI for all levels of PASI. Furthermore, results showed that not only changes in PASI but also its absolute value at the end of treatment has an impact for the patient reported assessment of therapy. Values < 3 in comparison to