Introduction: Rhino sinusitis is a group of disorders characterized by inflammation of the mucosa of both sinuses and nostrils. It is determined by environmental and host factors that interact causing a persistent inflammatory condition that causes remodeling of the mucosa. Chief among these are allergy and other immune disorders with colonization by infectious agents. Aim: To determine the demographic, clinical, immunologic and infectious agents involved in chronic Rhino sinusitis (CRS) and Recurrent Acute Rhino sinusitis (RAR) in children and adolescents undergoing functional endoscopic sinus surgery (FESS). Establish the possible associations of these characteristics with the need for re operation and recurrence of the disease. Material and method: Retrospective observational study that evaluated 28 children and adolescents involved in the ENT department at Clínica Las Condes, Santiago, Chile during the years 2000 to 2009. All study patients had preoperative Prick test, immune workout and intraoperative Para nasal mucosal biopsy and cultures of Para nasal secretion. Statistical analysis was performed using ANOVA test for descriptive analysis and cluster analysis with Fisher Exact test. Results were considered significant with p <0.05 Results: We analyzed 28 patients, 89.2% had positive Prick test and 53.6% showed biopsy with eosinophilic inflammatory disease. 17% had some type of immune deficiency. Positive intraoperative cultures were obtained in 71% of the samples, mostly aerobic agents (57.1%), with 14.2% anaerobes and negatives cultures for fungi. Twenty seven patients had postoperative follow-up of 5 years. Four of them (14%) had to be re-operated. During the monitoring period, 22% developed RAR. It was considered a poor surgical outcome the need for re-operation or recurrence of RAR. We couldn't find association of variables with a poor outcome after surgery. Conclusion: It was not possible to demonstrate an association between the interacting factors in the genesis of CRS and RAR and poor surgical outcome in the studied series. However, we do have an orientation of how is the immune status and bacteriology of children undergoing surgery in our midst.