Aim: To investigate the efficacy of adjunctive antimicrobial photodynamic therapy (aPDT) in patients with chronic periodontitis. Material and Methods: Meta-analyses were conducted according to PRISMA and Cochrane recommendations. Extensive literature and manual search were performed on eight databases. Mean difference (MD), 95% confidence intervals (CI) were calculated for probing depth (PD) reduction and gain in attachment level (AL). I2 test was used for inter-study heterogeneity, publication bias was examined by visual inspection of funnel plots. Results: From 992 identified and available records 811 were screened after removing of duplicates. 143 full-text reports were assessed and 81 studies were included in qualitative and 12 in quantitative synthesis (meta-analysis). The metaanalysis showed a statistical significant superior PD reduction (mm) and AL gain (mm) in test group (SRP + aPDT) over control group (SRP alone) for the follow-up of: 6 weeks (PD reduction) MD 0.15, 95% CI 0.06 to 0.25, p=0.001; 12 weeks (PD reduction) MD 0.17, 95% CI 0.16 to 0.18, p0.00001; 12 weeks (AL gain) MD 0.24, 95% CI 0.10 to 0.38, p=0.007. For the follow-up of 6 months the meta-analysis showed a not statistical significant difference between test and control group: 6 months (PD reduction) MD 0.08, 95% CI -0.25 to 0.42, p=0.63; 6 months (AL gain) MD 0.20, 95% CI -0.08 to 0.48, p= 0.16. Conclusion: While there is strong clinical evidence of short-term benefits for PD reduction (mm) and AL gain (mm) weak evidence is available for long-term benefits of adjunctive antimicrobial photodynamic therapy in chronic periodontitis. Keywords: adjunctive photodynamic therapy, chronic periodontitis, meta-analysis