This study was conducted to compare the masticatory muscle activity in patients wearing implant supported overdentures constructed with anatomic teeth according to lingualized occlusion concept (balanced occlusion) and implant supported overdenture constructed with non-anatomic teeth according to zero degree teeth with compensating curve (balanced occlusion).Seven completely edentulous patients were selected, free from anyneuromusculardisorders. The age range was within 45-55 years.Patients had received two implants in the mandibular canine regions. The implants were immediately loaded with implant overdentures retained with two ball attachments.The prosthetic treatment included the construction of two competedentures before implant installation.The first denture had the teeth set according to the Lingualized occlusion concept.The other denture was constructed with zero degree teeth with compensating curve. The patients had received implant supported overdenturewith lingualized occlusion concept (balanced occlusion). EMG of temporalis and masseter muscles was evaluated at the overdenture insertion visit, 1 month, 3 months after denture insertion.The muscle activity was evaluated during mild and maximum clenching of masseter and temporalis muscles.Patients were then derived from their overdentures for 1 month to allow elimination of the adaptability of muscles to the denture.After that patients received theoverdentures with non-anatomic teeth. The EMG was evaluated at denture insertion, 1 month, 3 months after denture insertion.Data were collected, tabulated and statistically analyzed.The results of the present study revealed that:• There is nosignificant difference between working and balancing side •The lowest muscle activity was recorded with overdentures with the lingualized occlusion concept. •The highest muscle activity was recorded withoverdentures with non-anatomic teeth arranged according to zero degree teeth with compensating curve.