To study the microbiological profile in patients with chronic rhino-sinusitis. To correlate disease severity with the presence of biofilms and host risk factors. To assess outcome of Sinus Surgery 2 weeks post operatively in terms of presence of bacteria and their ability to form biofilm. Prospective study. 50 cases of chronic rhino-sinusitis requiring Functional Endoscopic Sinus Surgery admitted in SDM Hospital, Dharwad, Karnataka were studied using intra-operative mucosal samples for microbiological analysis. The organisms isolated were tested for biofilm forming ability using three in vitro tests. Severity of disease was assessed using SNOT 22 scoring system. Of 50 cases studied, 66% showed presence of chronic rhino-sinusitis with polyposis and had higher SNOT scores compared to those without polyps. Bacterial isolates were obtained from only 17 samples. species was isolated from 16 samples and from one. 11 spp. isolates showed biofilm forming ability in vitro. Postoperative events in 3 cases yielded biofilm-forming was the most dominant organism isolated and 11 isolates were biofilm formers. Thus the detection of biofilm forming organisms can be considered as a negative prognostic indicator and should forewarn the surgeon about the risk of recurrence.