BACKGROUND This retrospective study compared the functional results of unilateral mandibular condylar process fractures treated either by open reduction or by closed treatment. METHODS Sixty-six patients with unilateral mandibular condylar process fractures were reviewed. Thirty-six patients received open reduction, and the other 30 underwent closed treatment (intermaxillary fixation only). Each group was further divided into condylar and subcondylar subgroups according to fracture level. The functional outcome was evaluated by posttreatment occlusion status, maximal mouth opening, facial symmetry, chin deviation, and temporomandibular joint symptoms. RESULTS Patients undergoing closed treatment exhibited more condylar motility than those treated by open reduction. Patients in the condylar subgroup with open reduction presented less chin deviation (21.43%) compared with those with closed treatment (56.25%; p = 0.072). Although a greater severity of subcondylar fractures existed in patients treated with open reduction, patients treated with open reduction or closed treatment did not reveal a significantly functional difference. CONCLUSIONS The present study revealed that patients with condylar neck or head fractures gained more benefits from open reduction in terms of chin deviation and temporomandibular joint pain. For subcondylar fractures, open reduction provides satisfactory functional results in patients with severely displaced fractures.