In vitro study was done to compare between single implant and two implants with locator attachment and their effect on the implants and supporting structure. Two mandibular acrylic models were made with placement of one implant at the midline and placement of two implants in the canine region both with locator attachment .Each implant was 3.8 mm in diameter and 12 mm in length. Channels were done in each model mesial and distal to the implants to receive the strain gauge. Each attachment was fitted to its overdenture .The acrylic model was placed on the lower flat metal plate of the testing machine. A loading device (universal-testing machine) was used to apply standardized static load. Loads were applied with magnitude of 100N. A special load applicator was used to apply standardized static load. Loading performed unilaterally in vertical direction at right 1st molar on both model. Comparing the results of single implant and two implants with locator attachment and their effect on the implants showed no significant difference between them (p value>0.05). So it can be concluded that post loading implant survival of single implant overdenture is not significantly different from two implants overdenture with locator attachement.