Purpose: The purpose of this preliminary study was to examine the influence of overdenture attachment height and shape on lateral force on implants and denture displacement. Materials and Methods: A straight model was fabricated to simulate the edentulous ridge. Two strain gauges were attached to the mesial and distal surfaces of the implant in the canine area. Five types of ball attachments and three types of Locator attachments with three types of replacement male attachments were used. A vertical load of 49 N was applied. The lateral force on the implant and the denture displacement were measured. Statistical comparisons were performed using one-way analysis of variance, Tukey post hoc comparison test, and multivariate analysis. P .05 was considered significant. Results: Ball attachments of 4-mm height exerted the highest lateral force on the implant, and the greatest displacement was also observed with attachments of 4-mm height. Different lateral forces were observed for different shapes of ball attachments, but there were no significant differences in denture displacement among the shapes. For Locator attachments, the highest lateral force was observed with the white male type, and the greatest denture displacement occurred with attachments of 4-mm height. There were no significant differences among male white, pink, and blue types. Conclusion: The height of the stud attachments in implant overdentures had a marked effect on the lateral force on implants and on denture displacement. To protect implants supporting an overdenture and to prevent bone resorption, the height of the attachment should be carefully considered.