An intervention experimental study was conducted to assess the impact of Peridontitis education program (PEP) for Peridontitis patients in King Abdel Aziz University Hospital (KAAUH) in Riyadh City. The program was administered to 103 patients through one session and one immediate assessment. Another 103 patients formed the control group. The results showed that the mean knowledge score, the mean scores of the perceived seriousness (p. seriousness), p. benefits, and p. barriers of intervention group were significantly higher than the control group. Stepwise multiple regression models revealed that total knowledge, perceived benefits, patients' work, and family size were predictors of patients' practice of control group (β=0.287, 0.218, 0.194, and 0.192). Total knowledge, patients' work and total health beliefs model (HBM) score were predictors of patients' practice of the intervention group (R²=0.303). The study recommended the replication of such program and a more long term one to have more improvement in patients' knowledge, all beliefs, and practice.