Purpose: To evaluate the effect of laser bio stimulation with split ridge technique on bone loss around 4 implant supported bar overdentures . The evaluation was made  radiographically  to measure vertical bone height changes around implants after six months and one year from mandibular over denture insertion Materials and Methods Six patients with totally edentulous jaws, their age ranged from 50 to 65 years  (mean 58 year) ,  were involved in this study , For each patient, a conventional complete denture was constructed and delivered, then followed up weekly for one month for correction of any complaints.Following the two stage surgical technique and delayed loading protocol four Implants were placed in the interforaminal region  after  alveolar ridge splitting using sequential series of chisels .the patients were randomly classified into two equal groups: group(A) received laser biostimulation immediately after implant placement ,group (B) without laser biostimulation.custom made  round bar was made for each patient.then fabrication of mandibular complete overdenture. Radiographic evaluations were performed immediately (T0), 6 months (T6), and 12 months (T12) respectively . Results The result of this study showed that the vertical bone loss around all implants in the two groups after one year of loading was within the accepted limits of implant success (less than 1.5mm). Also, these results showed no statistically significant difference in vertical bone loss around all implants in both groups during the 2nd 6 month after loading. When comparing anterior and posterior implants in each group during the year of the study, posterior implants showed higher bone loss than anterior implants .