Uncomplicated chronic rhinosinusitis (CRS) is generally treated with medical therapy initially and surgery is contemplated only after medical therapy has failed. However, there is considerable variation in the medical treatment regimens used and studies defining their efficacy are few. The aim of this study was to determine the proportion of patients treated medically who responded sufficiently well so that surgery was not required. Subgroup analysis to identify clinical features that predicted a favorable response to medical therapy was also performed. Eighty patients referred to the Otorhinolaryngology Clinic at North Shore Hospital were treated with a standardized medical therapy protocol (oral prednisone for 3 weeks, oral antibiotics and ongoing saline lavage and intranasal budesonide spray). Symptom scores were collected before and after medical therapy. Clinical features such as presence of polyps, asthma, and aspirin hypersensitivity were recorded. Failure of medical therapy was defined as the persistence of significant CRS symptoms, and those patients who failed medical therapy were offered surgery. Follow-up data were available for 72 (90%) patients. Of this group, 52.5%, (95% CI, 42.7%, 62.2%) failed to respond adequately to medical therapy and were offered surgery. The remaining patients (37.5%) were successfully treated with medical therapy and did not require surgery at the time of follow-up. The premedical therapy symptom scores were significantly higher than the postmedical therapy symptom scores (p < 0.01). The symptom scores of those patients postmedical therapy who proceeded to have surgery were significantly higher than the group who responded well to maximum medical therapy (MMT) and did not require surgery (p < 0.0001). There were no significant differences in the proportion of patients with asthma, aspirin sensitivity, or polyps between the groups failing or not failing MMT. In approximately one-third of patients with CRS, medical therapy improved symptoms sufficiently so that surgical therapy was avoided. Patients with more severe symptoms tended not to respond as well as those with less severe symptoms. Long-term follow-up is required for the group of responders to determine how many will eventually relapse.