Objective: This study aimed at comparing clinically and radiographically the therapeutic effect of low level laser therapy and demineralized bone matrix, used in management of periodontal intrabony defect. Subjects and methods: Thirty two non-smoking patients aged between 28-51 years with severe chronic periodontitis participated in this randomized clinical study. Patients were randomly assigned into one of 2 groups (16 patients each): demineralized bone grafting alone of the intrabony defect, control group (Group I), demineralized bone grafting and the application of low level laser therapy (LLLT) (Group II). Clinical and radiographic parameters including plaque index, bleeding index, probing depth, clinical attachment level (CAL) and intrabony defect depth were reassessed at 6 months after surgery. Results:  Specifically, LLLT treated sites (Group II) showed statistically significant differences regarding pocket depth and CAL compared with Group I. Intrabony defect depth was significantly reduced for LLLT group compared to that of Group I control. Conclusion: The use of LLLT as an adjunct with demineralized bone matrix (DBM) in the treatment of intrabony defects was more significant in improving the probing depth, CAL and intrabony defect depth than using DBM alone.