Design quality of websites is known to have a positive impact on user attention. Although there are lots of papers that investigate design qualities of websites in the literature, none of them takes into account interactions among design characteristics. The main objective of this study is to evaluate the perceived design quality of websites while considering the interactions among design characteristics. For this purpose, a new approach named the quality evaluation model (QuEM), which includes fuzzy set theory, the decision-making trial and evaluation laboratory method (DEMATEL), and generalized Choquet integral techniques, is proposed. The critical design characteristics of websites are determined based on interactions among them by using DEMATEL. Then, the degrees of importance are utilized in the generalized Choquet integral to evaluate the perceived design quality of website designs. Fuzzy set theory is utilized to cope with ambiguity in the linguistic evaluation of the different design characteristics and supports the analysis of the collected data. Finally, the proposed method is applied for the evaluation of the quality of the most used shopping websites in Turkey. (C) 2012 Elsevier B. V. All rights reserved.