Multidimensional scaling (MDS) offers a rigorous approach to many problems in perception, emotion, personality, and cognition, where the stimuli are too complex to be quantified by other means. In these procedures similarity ratings of the stimulus objects are modeled as points in multidimensional space, such that perceived similarity is represented by spatial proximity. The stimulus objects may be physical stimuli or words describing qualities of pain. In this study, Individual Differences Scaling (INDSCAL) was used to examine the dimensions of pain obtained from similarity judgments made to verbal descriptors of global pain by 16 patients suffering cancer-related pain and by 16 healthy volunteers. The INDSCAL analysis yielded similar two-dimensional solutions for both groups. The major dimension was magnitude of sensory pain: mild pain to intense pain. The second dimension, pain qualities, contained two components: a somatosensory attribute (e.g., burning) and an unpleasant affect attribute (e.g., miserable). The two groups differed in where they located certain descriptors in the space. For example, mild pain was more emotion laden for the cancer patients, but more of a somatosensory sensation for the healthy volunteers. Although much work remains to be done with a wider range of descriptors, it is clear that MDS procedures such as INDSCAL, have much to offer in the investigation of pain and other complex stimuli. (Author/ABL)