OBJECTIVES: In many countries, utility measures are required for allocation decisions. Unlike the EQ-5D (EuroQoL-5D), the DLQI (Dermatology Life Quality Index) has not been developed for the derivation of utilities. Purpose of this study was to develop and test an algorithm for the transformation of DLQI scores into EQ-5D utility scores. METHODS: Pre-existing data of two cross-sectional studies (for development, n = 1,511; for cross-validation n = 2,009) of German psoriasis patients were reanalyzed. Both EQ-5D global score and EQ-5D visual analogue scale (VAS) were used as utility measures. Correlations were computed to identify predictors of EQ-5D utility scores. Linear stepwise regressions were conducted using DLQI and further potential predictors to find the optimal mapping algorithm. RESULTS: Using only DLQI as predictor resulted in coefficients of determination of R2 = 0.235 (EQ-5D global score) and R2 = 0.242 (EQ-5D VAS). In the final algorithm, seven predictors were included which correctly predicted EQ-5D VAS for 60.4% (development database) and 60.8% of all patients (cross-validation database) within a range of ±15 units. The algorithm explained 31.3% of the EQ-5D variance in the development database and 26.8% in the cross-validation database. CONCLUSIONS: In spite of the wide definition of correct prediction (±15 units), utility scores of less than two thirds of the patients were predicted correctly. As opposed to the authors of two publications on earlier mapping approaches, we therefore conclude that mapping of DLQI on EQ-5D in psoriasis patients has considerable limitations in validity and clinical relevance.