The purpose of this study on hand injury from powered wood splitters was to describe injury epidemiology and anatomy, to rate injury severity, to evaluate the outcome after injury and to describe factors of possible importance for the occurrence of injury. By searching a computerized patient registry, 131 patients injured by wood splitters from 1995 to 2001 were identified. Information was obtained from hospital records and radiographs, a written questionnaire and a structured telephone interview. Injury severity was rated according to the Hand Injury Severity Scoring System (HISS system) and the Injury Severity Score (ISS). Outcome was evaluated with the Disabilities of the Arm, Shoulder and Hand outcome questionnaire (DASH) and, in 26 of the most severely injured patients, with the Sollerman test. Forty-six percent of the injuries occurred during April or May. Wedge splitters caused 82 % of all injuries and most often injured the index finger, while screw splitters caused 18 % of all injuries and most often injured the metacarpus. Screw splitters caused palmar perforation and thumb avulsion. Sixty-three percent of all patients had an amputation or devascularising injury. The reliability of HISS rating was good. The mean Hand Injury Severity Score (HISS) was 63 which is equivalent to a severe hand injury. The mean ISS was 3.7. Nineteen percent of patients had minor, 31 % had moderate, 23 % had severe and 27 % had major injury according to the HISS system. Children had more severe injuries than adults. There was no significant difference regarding HISS or DASH scores between wedge and screw splitter injuries. The mean DASH score was 15, indicating moderate residual sequelae, but patients without sequelae and patients with grave sequelae were found in all HISS severity grades. There was a weak but significant correlation between the HISS and DASH scores. The mean Sollerman score in the injured hand was 66, indicating significantly impaired hand function. Twenty-nine percent of splitters were home-made. Very few machines had the safety measures required by European Standards. Children were present during splitting in at least 15 % of cases. Not being alone at the machine was one cause of wedge splitter injury. Glove use was one cause of screw splitter injury. Hand injury from powered wood splitters is a significant problem. Many of the injuries are severe, and cause long term sequels and impairment of hand function. Prevention is essential and should focus on unsafe machines and dangerous patterns of use.