From January 1993 to December 1997, we treated 78 (75 fresh, 1 delayed union and 2 nonunion) fractures of the mid-third clavicle with open reduction and internal fixation using 3.8 mm Knowles pins. All patients used an arm sling for 2-6 weeks after surgery, and were told to avoid vigorous exercise or work with heavy loads for the next 6 weeks. 73 fractures healed within 6 months. 3 complications occurred relating to the surgical procedures. The final rate of bone union was 77/78, although 3 patients showed a delay in bone union and 1 fracture was revised because of a loosened Knowles pin. After a mean follow-up of 49 (24-86) months, the average shoulder function, as evaluated by a modified Constant-Murley score, was 97% versus the contralateral shoulder. We suggest that if surgery is indicated, open reduction and internal fixation using a Knowles pin is an effective method for managing mid-third clavicular fractures.