Background: Odontogenic sinus disease requires optimal management, which includes definitive management of the underlying dental pathology. Additional endodontic management of root canal, dental extraction, or apicoectomy. So, in patients who have failed initial medical and/or dental therapy, endoscopic sinus surgery (ESS) is recommended. However, the optimal timing for ESS is still unclear in literatures. Objective: to find the optimal time for ESS in patients with odontogenic sinusitis (ODS) after the failure of the primary medical treatment. Patients and methods: This research was performed on 25 ODS patients: 14 males and 11 females. After the failure of primary medical treatment, these patients had preferred and undergone ESS. Another 21 patients who had dental intervention were used for comparison (12 females and 9 males). Assessment of the outcome was performed by the Sino-nasal Outcome Test-22 (SNOT-22) questionnaire for all patients. Results: The patients improved as there is a decrease in SNOT-22 score from 38.75 ± 9.56 to 15.7 ± 18.12 in ESS group (p =0.000), more than dental group that decreased from 37.93 ± 11.3 to 28.42 ± 21.7 (p= 0.039). It was observed that the SNOT-22 score increased as the time of intervention increased, so it is advised to start ESS as early as possible to have a successful surgery. Conclusion: An early ESS of ODS is a clue for a fast and successful treatment outcome. So, it is recommended that primary ESS is first to be performed, particularly in patients sufferings severe unresolved sinusitis, followed by dental treatment, which is the ideal protocol for management of ODS.