The objective of this study that included 34 patients with psoriasis was to assess the reliability of the disease severity measures (i.e. Psoriasis Area and Severity Index - PASI) and the reliability of the health related quality of life measures (i.e. EuroQol EQ-5D Quality of Life Scale - EQ-5D, Dermatology Life Quality Index - DLQI and Psoriasis Disability Index -PDI). High interobserver correlation reliability and good test-retest reliability of PASI scores, as well as good test-retest reliability of EQ-5D, DLQI and PDI scores were achieved. Correlation coefficients between the test and retest scores on DLQI and PDI were higher than those on the dimensions and on EQ-VAS in EQ-5D. Disease severity scores given by PASI and the quality of lify scores given by EQ-5D, DLQI and PDI offered the reliable assessment of both the psoriasis severity and the quality of life of the people with psoriasis.