Chronic rhinosinusitis is a long term inflammatory condition that affects the mucosa of the nose and paranasal sinuses chronic rhinosinusitis can be associated with nasal polyposis or without nasal polyposis If patient does not respond well to the maximum drug treatment and having nasal polys  functional endoscopic sinus surgery FESS will be the treatment of choice FUNCTIONAL ENDOSCOPIC SINUS SURGERY is a non invasive or minimally invasive surgical procedure which restores the paranasal sinus function it re establishes physiological pattern of ventilation and mucociliary clearance Multiple techniques are already in use to improve surgical field by reducing blood loss like hypotensive anesthesia GA  bipolar diathermy topical vasoconstrictors local injection of epinephrine reverse Trendelenburg position None of them permanently provide an ideal surgical field Bleeding in FESS remains a challenge for surgeons and anesthesiologists Desmopressin is 1-deamino-8-D-arginine vasopressin  is a synthetic peptide and selective V2 agonist synthetic analogue of the antidiuretic hormone L-arginine vasopressin  it affects hemostasis through increasing plasma concentrations of tissue plasminogen activator and endothelial factor VIII von willebrands factor thus improving platelet adhesiveness exerting a probable effect on vascular stability Recently hemostatic effects of desmopressin have been considered by surgeon Unique feature of desmopressin its abilitity to create a localized effect focusing its action specifically at the site of bleeding without affecting the systemic hemostasis is utilized in this study So this study is conducted to evaluate the effect of intranasal desmopressin spray as a premedication before functional endoscopic sinus surgery as a noninvasive technique and with minimal adverse effects to improve quality of surgical field