A descriptive severity scoring system for injuries to the hand, distal to the carpus, has been designed. Each ray of the hand is assessed separately. Each ray's score is then multiplied by a weighting factor for that ray and added to the scores of the other rays to obtain a total score for the injury. This system has been tested on a series of specimen injuries and compared with the opinion of experienced hand surgeons. A retrospective study of hand injuries has also been conducted, and the Hand Injury Severity Score (HISS) has been found to closely correlate with return to work. Four grades of increasing severity of hand injury have been described. Although this system has been designed as a research tool, it is envisaged that it would be a useful immediate measure of severity and a guide to likely outcome.