Although widely used, there have been few investigations of the factorial validity of the short-form McGill Pain Questionnaire (SF-MPQ; Melzack, 1987). Confirmatory factor analysis was performed on item responses to the SF-MPQ obtained from 188 patients with chronic back pain. Consistent with the original structure proposed by Melzack (1987), results indicated that the SF-MPQ is best represented by a two-factor solution. However, these findings are contrary to results obtained by Burckhardt and Bjelle (1994) who, using their Swedish version of the SF-MPQ, obtained a three-factor solution. Potential explanations for the disparity between the results of the two studies are explored and recommendations for continuing clinical and research applications are offered. Copyright 2001 European Federation of Chapters of the International Association for the Study of Pain.