Background: Functional endoscopic sinus surgery (FESS) is considered as one of the most common surgical procedure. General anesthesia (GA) is usually required during FESS. Regional analgesic techniques can use during GA that is inhibits the intra- and the post-operative detrimental stimuli. Objective: To evaluate the effects of bilateral sphenopalatine ganglion block (SPGB) in FESS by using different types of local anesthetic agents. Patients and Methods: A double-blinded, randomized, controlled-trial study was performed on 80 patients undergoing FESS with bilateral SPGB under GA. This study was conducted at departments of Otorhinolaryngology and Anesthesia & Intensive care, Al-Jafel International Hospital, Riyadh, KSA. The current study was conducted since May 2018 till January 2020. The patients were categorized into 4 groups; group I using (bupivacaine 0.5%), group II using (ropavacine 0.75%), group III using (xylocaine 2%), and group IV using (saline) as a control group. Observed variables included hemodynamic parameters, surgical field visibility, intra-operative blood loss, post-operative analgesia use, and complications related to the used technique. Results: Averages of the heart rate, mean arterial blood pressure, bleeding, operative time, and visual analogue scale (VAS) in the three groups were statistically significant different from the controls (P=000). The clarities of the operative field and bleeding amount in the three groups separately were statistically significant different from the controls (P=0.000). The differences in the post-operative complications in the three groups and the controls were statistically insignificant except for group III. The differences in the analgesics usage in the three studied groups and the controls were statistically insignificant except group I. Conclusion: Using of bilateral SPGB in FESS under GA is proved to be of great importance in reducing the heart rate, arterial blood pressure, bleeding, operation time, and VAS in the studied groups. Further, xylocaine 2% is significantly reducing the post-operative complications. Also, bupivacaine 0.5% is significantly reducing the analgesics usage.