Objective To investigate the etiology, diagnosis, and treatment of acute carpal tunnel syndrome (ACTS) after reduction of Colles’ fracture. Methods Between December 2006 and June 2010, 22 patients with ACTS after reduction of Colles’ fracture were treated with expectant treatment and surgical treatment. There were 9 males and 13 females with an average age of 46.2 years (range, 23-60 years). Fractures were caused by traffic accident in 9 cases, fall ing in 8 cases, fall ing from height in 2 cases, hitting in 2 cases, and crushing in 1 case. The mechanism of fracture was direct violence in 3 cases and indirect violence in 19 cases. According to Gartland ＆ Werley classification, there were 2 cases of type I, 5 cases of type II, 14 cases of type III, and 1 case of type IV. Closed reduction was performed in 19 cases and open reduction and internal fixation (ORIF) in 3 cases. The average symptom time of ACTS after reduction of Colles’ fracture was 11.6 hours (range, 1 hour 30 minutes to 48 hours) in patients undergoing closed reduction and was 24 hours in 1 patient and 2 weeks in 2 patients undergoing ORIF. Expectant treatment was performed first, the forearms were put in neutral position in closed reduction cases; if there was no rel ief of ACTS symptom 1 week later, the mixture of 1 mL glucocorticosteroid and 1 mL 2% l idocaine was injected into carpal tunnel once a week for 2 weeks. The mixture was injected into carpal tunnel directly once a week for 2 weeks in ORIF cases. In the patients who failed to expectant treatments, ORIF was performed. Results In 7 cases of type III that failed expectant treatment, ACTS symptoms were rel ief completely after ORIF. All the 22 patients were followed up 12 months on average (range, 8-18 months). The average time of complete disappearance of median nerve compression symptom was 11 days (range, 2-25 days). All the patients had normal finger motion, sensation, and opposition of thumb with no sensation of anaesthesia and pinprick. The results of Tinel test, Phalen test, and Reverse Phalen test were all negative. The X-ray film showed good fracture reduction and heal ing with an average heal ing time of 6 weeks (range, 3-14 weeks). According to GU Yudong’s criteria for functionalassessment, the results were excellent in 18 cases and good in 4 cases; the excellent and good rate was 100%. Conclusion Malposition, displacement of fracture fragments, and ulnar deviation of the wrist after plaster immobil ization are the mostimportant risk factors for ACTS. Expectant treatments are recommended in patients with Colles’ fracture of types I, II, and IV,but surgical treatment is the first choice for Colles’ fracture of type III.