The purpose of this study was to identify variables associated with post-operative pressure sore incidence. The data were derived from a sequential, double triangular, randomised, blinded, controlled trial of the intra-operative use of a visco-elastic polymer pad conducted at two centres. Of 446 surgical patients recruited the main endpoint was assessed for 416 patients of whom 65 (15.6%) had a post-operative pressure sore. Analysis determined that the probability of a patient developing a pressure sore was associated with increased number of hypotensive episodes and mean core temperature during surgery, and reduced mobility Day 1 post-operatively. The development of a probability equation illustrates the future potential of prognostic factor research in the development of risk assessment tools and their application within clinical settings.