In part one of this article, the concepts of an injury threshold were explained and it was shown that the Reswick and Rogers pressure-time curve is inaccurate at the extremes of the timescale. It was also shown that their curve cannot be used for studying deep tissue injuries, and that it is likely to be irrelevant for studying most pressure ulcers. The second part of this article describes recent research work focusing on tissue injury thresholds as related to pressure ulcers, with particular emphasis on thresholds that are specific for deep tissue injuries. Clinical implications are also discussed, with particular reference to patients who are obese and those with muscle atrophy.