Purpose: The aim of this crossover study was to evaluate electromyographic (EMG) connectivity of masseter muscle with different attachments used to retain implant overdentures in patients with atrophied mandibular ridges. Materials and Methods: Twenty-four edentulous participants with atrophic mandibular ridges received conventional dentures (control). Three months after the adaptation period, two implants were placed in the canine areas of the mandible. After osseointegration, each participant was successively given the following prostheses in a crossover manner: (1) ball-retained overdentures, (2) bar-retained overdentures, and (3) Locator-retained overdentures. The EMG parameters (amplitude, chewing area, chewing rate, duration of chewing cycle, duration of chewing burst, and chewing time) were measured 3 months after wearing the following prostheses: conventional dentures, ball overdentures, bar overdentures, and Locator overdentures. Measurements were made during chewing of hard (carrot) and soft (cake) foods. Results: The highest EMG activity/amplitude, chewing area, duration of chewing cycle, and duration of chewing burst were noted with ball overdentures, followed by bar overdentures and Locator overdentures, and the lowest values were observed with conventional dentures. The highest chewing rate and masticatory time were noted with conventional dentures, and the lowest values were observed with ball overdentures. With the exception of chewing area, no significant differences in all tested parameters between bar overdentures and Locator overdentures were observed. Except for duration of chewing cycle, all tested parameters were significantly higher during chewing of hard food than soft food. Conclusion: Within the limitations of this study, twoimplant overdentures recorded higher muscle functions compared to conventional dentures regardless of the type of attachment used. For such overdentures, ball attachment may be recommended over bar and Locator attachments, as it was associated with improved muscle activity and function. Keywords: atrophied ridge, attachments, EMG activity, implants, overdentures