Purpose: To evaluate effects of the adjunctive subgingival application of sodium hypochlorite on clinical outcome following nonsurgical periodontal treatment. Materials and Methods: A search protocol was developed to answer the following focused question: 'in patients with periodontitis, does adjunctive subgingival application of sodium hypochlorite have additional clinical benefits compared to subgingival debridement alone?' Randomised controlled clinical trials (RCTs) published up to January 30, 2020, with at least 6 months of follow-up, in which sodium hypochlorite was used as an adjunct in nonsurgical periodontitis treatment were included. The search was limited to the English language. Results: Out of 355 studies retrieved, the search resulted in two publications that fulfilled the inclusion criteria. The adjunctive application of sodium hypochlorite did not provide additional beneficial effect in terms of changes in the evaluated clinical outcomes (i.e. probing depth values [PDs], clinical attachment level gain [CAL] and bleeding on probing [BOP]) when compared to mechanical instrumentation alone over the 12-month investigation period (p > 0.05). Conclusion: The available data have failed to show any additional clinical benefit following the use of sodium hypochlorite in conjunction with nonsurgical periodontal therapy. Keywords: periodontitis, review, therapy, treatment