Aim of the study: This study aims to assess the effect of oral clonidine premedication on blood loss and the surgical field quality during endoscopic sinus surgery in individuals with bilateral sinonasal polyposis. Patients and methods: At the Beni- Suef University Hospital, a randomised, controlled, double-blind clinical experiment was done. Approval from research ethics committee of faculty of medicine of Beni-Suef University and an informed consent from patients diagnosed as sinonasal polyposis was obtained, in the duration from June 2019 to February 2020. Forty patients were randomly assigned to equal groups; group 1 (20 patients) received oral clonidine 200 micrograms (the recommended dose) 1 to 1.5 hours before the time of operation and group 2 (20 patients) did not receive clonidine. Surgeries in both groups were done using hypotensive anesthesia in the form of deep general anesthesia and heavy analgesia under general anesthesia. An uncinectomy, middle meatal antrostomy, anterior ethmoidectomy, posterior ethmoidectomy, and, if necessary, sphenoidectomy were performed as part of endoscopic sinus surgery (ESS). Results: The blood loss in the jar and the total blood loss in group 2 are statistically significant higher than group 1 (P-value<0.05). That there was a statistically significant difference between the two groups regarding the mean Boezart scale and its categories (P-value<0.05). There was a statistically significant increase of the intraoperative time in group 2 than group 1 (P-value<0.05). In conclusion, the pre-medication with clonidine improves hemodynamic status, surgical field, decrease the blood loss inside the jars and the total blood loss and subsequently decrease the intraoperative time.