AIM: The aim of the present study was to assess and compare the clinical efficacy of local probiotic Lactobacillus reuteri (L. reuteri) and systemic antibiotics as adjunct to scaling and root planing (SRP) in the treatment of chronic periodontitis (CP). METHODS: Thirty systemically-healthy participants (15 probiotic and 15 antibiotic), clinically diagnosed with CP, were enrolled. All patients underwent SRP. Adjunctive probiotics were administered twice daily for 3 months, whereas a combination of amoxicillin and metronidazole were given three times daily for 7 days. RESULTS: Intragroup analysis showed statistically-significant improvement in all clinical parameters: plaque index, bleeding on probing, periodontal pocket depth, and clinical attachment level gain at each follow-up visit. However, intergroup comparison of clinical periodontal parameters did not show statistical significance. CONCLUSION: The adjunctive use of L. reuteri and systemic antibiotics along with SRP showed similar improvement in all clinical periodontal parameters. This indicates that both adjunctive therapeutic agents showed similar efficacy in resolving inflammation and improving periodontal outcomes.