Purpose: The purpose of this study was to compare the electromyographic (EMG) activity level and signs and symptoms in patients with myogenous temporomandibular disorders (TMD) treated with two different types of occlusal devices. Materials and Methods: Eleven TMD patients were treated with maxillary occlusal devices. The first group received a flat-plane stabilization occlusal device, while the second group received an anatomic occlusal device that maintained the anatomy of the original occlusal surfaces. The severity of signs and symptoms and the masseter EMG activity were recorded and evaluated before treatment and at 72 hours, 2 weeks, and 4 weeks following the delivery of the occlusal device. EMG activity was measured during maximum clenching and during chewing on the right and left sides. The EMG was also recorded for seven normal subjects as a control group. Results: All patients showed reduction of reported and clinically found muscle pain, with no statistically significant differences between the two groups. A reduction in the EMG activity level at maximum clenching was seen in both patient groups, but was significant only with the anatomic occlusal device. Mean EMG activity during chewing was highly variable within and between groups. Conclusion: The subjective and objective improvements with both types of occlusal devices suggest that either type of occlusal device can be beneficial to TMD patients.