Introduction: The present one-month study was done to assess the effect of topically-applied toothpaste containing metronidazole (MTZ) and chlorhexidine (CHX) alone or in combination together using as an adjunct both during basic non-surgical therapy in patients with adult periodontitis (AP).Methods: Eighty eligible adult (with one probing pocket depth (PPD) of >= 5 mm) patients (50 females and 30 males, average age of 35 years) with moderately advanced chronic periodontitis were admitted. Plaque index (PI), PPD, clinical attachment level (CAL), gingival index (GI) and Bleeding on probing (BoP) were assessed before (at baseline) and after (weeks 2, 3 and 4) treatment. The patients were then randomly assigned to one of four treatment groups; placebo (toothpaste without antibacterial agents), MTZ 1%, CHX 0.2% and combined toothpaste of MTZ 1% and CHX 0.2%. Clinical re-examination was performed at the end of week 2, week 3 and week 4 after application of toothpaste. Results: At the end of one month trial, some significant improvements were seen in PPD, GI, PI and BoP. All study groups, except in MTZ showed a significant improvement in CAL. The greater improvement in clinical manifestations of PI, GI and BoP was seen in combined treatment group compared to others (0.05.)Conclusion: according to the results, combination therapy of MTZ 1% and CHX 0.2% together in the toothpaste could be more effective in improving the parameters than each of them alone.