Introduction: Considering the importance of periodontal supportive treatment in long-term preservation of teeth and prevention of recurrence of periodontitis, it was aimed to identify the factors affecting patients' compliance in continuing periodontal treatment. Methods: This cross-sectional study conducted on 233 patients referred to the periodontics and oral health and community dentistry departments and were candidate for non-surgical periodontal treatment. Data were collected by researcher-made questionnaires and the association between demographic characteristics and some possible external and internal influencing factors with the patients' attendance in first follow-up was investigated. Results: Only 39% of patients participated in the first follow-up. The patients' previous internal desire to participate in follow-up sessions had a statistically significant relationship with their compliance (P=0.001). Age, gender, education level, economic status, type of employment of patients and smoking did not show any significant relationship with following up the treatment. None of the investigated factors such as lack of time, the quality of mutual communication between the dentist and the patient, satisfaction with the treatment, providing health instructions by the dentist and explaining the consequences of not continuing the treatment to the patient did not affect the probability of the patient's adherence to continuing the treatment. Conclusion: There is no definite factor to increase the compliance rate of patients and it is necessary to increase the patients' motivation with different intervention methods, in a way that the importance of participating in the follow-up sessions is clarified for the patients.