Objectives: To evaluate the effects of ozone in periodontal treatment in dental practice. Methods: An evaluation of the current state of knowledge regarding the application of ozone in periodontal treatment revealed limited available literature. Therefore an audit was conducted in dental practice in order to evaluate the effects of ozone in periodontal treatment. Twenty-five patients were treated with gaseous ozone after having had failed conventional periodontal treatment. BPE scores and the six deepest pockets were measured in each patient before and after the use of ozone. Results: From the initial number of twenty-nine patients selected, twenty-five patients attended both follow up appointments. Based on BPE scores, twenty of the patients have overall improvement while five of the patients continued to have deterioration. Eight patients had an improvement in depths of periodontal pockets by three millimetres, sixteen patients had improvement by one to two millimetres and one patient did not improve. The depth of pockets after the use of ozone decreased significantly (P < 0.001). Conclusion: The audit revealed that gaseous ozone significantly (P < 0.001) reduced the depth of pockets in patients with periodontal disease. The positive results encourage further investigation in the subject.