Abstract: Objective To study whether delayed operation is related with shoulder joint function and complications in treatment of unstable distal clavicle fracture(Neer typeⅡ) with clavicle hook plate. Methods Forty-six patients with Neer typeⅡfracture who underwent clavicle hook plate fixation in our hospital from January 2009 to February 2012 were retrospectively analyzed. The patients were divided into acute operation(<3 weeks) group(n=29) and delayed operation(≥ 3 weeks) group(n=17) according to their operation time. Shoulder joint function of the patients was assessed according to their constant shoulder joint scores and postoperative complications were recorded. Results The 46 patients were followed up for an average period of 12.5 months(range 6 to 18 months). X-ray examination showed that the unstable distal clavicle fracture was healed in 43 patients(95.3%). The average constant score was higher in acute operation group than in delayed operation group(94 vs 73, 82-100 vs 68-85, P=0.008). The incidence of complication was higher in delayed operation group than in acute operation group(35.3% vs 6.9%, 6/17 vs 2/29, P=0.045). Conclusion Surgical operation time plays an important role in treatment of Neer typeⅡfracture. Delayed operation is related with the poorer shoulder joint function and higher complication rate of patients with Neer typeⅡfracture.