Purpose: this study aimed to evaluate role of Trigeminal somatosensory evoked potential in evaluation of infraorbital nerve function. Patients and methods: twelve adult patients with unilateral zygomaticomaxillary complex fractures were treated by open reduction and internal semirigid fixation using 2.0 mm titanium plates and screws. These patients were classified into (2) groups, group (I) including six patients suffered from displaced zygomaticomaxillary complex fractures and group (II) including six patients suffered from nondisplaced zygomaticomaxillary fractures. The neurosensory function of the infraorbital nerve was detected both subjectively through patient’s questionnaire and objectively through detection of the trigeminal somatosensory evoked potential (TSEP) preoperatively, 3 and 6 months postoperatively. Results: the results of patient’s questionnaire showed statistical significant differences between the two groups through all periods of followup as regards to presence of numbness sensation in the upper lip, lower eye lid and skin of the lateral aspect of the nose Also, the results of (TSEP) revealed statistical difference between mean and standard deviation values of latency in both groups. Conclusion: Trigeminal somatosensory evoked potential (TSEP) is considered as an efficient, sensitive and noninvasive method for testing the neurosensory function of the infraorbital nerve following treatment of zygomaticomaxillary complex fractures.