A randomized controlled clinical trial was conducted on 16 patients (8 males and 8 women) who were diagnosed chronic periodontitis. All the patients has been divided by randomization in two groups: control group treated with placebo gel and experimental group treated with gel based on ozonated EVO olive oil. Both group after the evaluation of inclusion and exclusion criteria during the first visit, were subjected to hygiene treatment of removal tartar deposit, considered as standard of therapy for periodontitis. After 15 days the hygiene treatment, patients were been randomized in two groups following the flow chart (t0) starting with: periodontal probing, microbiological samples and the first administration of gel. Next week (t1), has been collected the compliance and did the second administration of gel; the procedures will be the same also for another week (t2), until the last week (t3) when has been registered the second periodontal probing and did the second microbiological samples. Data were collected to software Microsoft Excel and all the data analysis were conducted on this software to highlight significant differences between both groups. As the primary outcome was continuous variable and assuming normal distribution bilateral parametric test T-student was performed. An alpha error of 5% was considered, Beta error was not calculated as this was a pilot study.