Aim: This study was conducted to evaluate the effect ball and equator attachments strain (invitro study) of mandibular over denture retained by single midline implant for completely edentulous patient. Subjects and methods: Ten complete lower dentures have ball attachment and another ten complete lower dentures have equator attachment were constructed on ten acrylic models covered by rubber material to simulate oral mucosa have single midline implant, strain were evaluated around the mandibular midline implant and in the posterior area using strain meter after unilateral and bilateral loading by universal testing machine for each abutment individually. Results: When comparing strain in the peri implant area under unilateral and bilateral loading there is a significant increase in strain for ball than equator with insignificant increase in strain in the posterior area. Conclusion: According to this study strain around implant and posterior residual ridge of ball attachment more than equator one for mandibular over denture retained by single midline implant.