Introduction: Nasal drainage has been used for many years in the management of nasal diseases. However, just a few studies were performed to confirm its efficacy. Objective: To analyze clinical evaluation of patients who underwent FESS, by comparing the use of hypertonic and normal saline solutions. Material and Methods: We developed a prospective and double-blind study including 30 patients in immediate postoperative of FESS (chronic sinusitis and/or nasal polyposis). They were randomized into two identical groups, each one receiving either normal saline (NaCl 0,9%) or buffered hypertonic saline (NaCl 2% + NaHCO3 6%). Seven parameters were evaluated one week and one month after surgery: symptoms (headache, nasal obstruction, hyposmia and nasal secretion) and endoscopic examination (edema, crusts and secretion). Results: Patients who received buffered hypertonic solution had better average outcomes. However, statistic significance was observed only in four parameters with one week following FESS: nasal obstruction, hiposmia, edema and presence of nasal secretion in nasal endoscopy. After one month of postoperative, the differences were less remarkable. Three out of 15 patients who used hypertonic saline couldn't bear the treatment due to nasal itching and pain. Conclusions: Buffered hypertonic saline promotes faster clinical improvement of patients undergoing FESS, when compared to normal saline; Buffered hypertonic saline is not as well tolerated by patients as normal saline.