Objectives: To compare the 2 long-term medical strategies in chronic rhinosinusitis without nasal polyps (CRSnNP) and to identify the role of gastroesophageal reflux disease (GERD) and Helicobacter pylori as factors of treatment failure. Material and Methods: Fifty-seven patients with CRSnNP were randomized into 2 therapeutic groups. The first group was treated with 4 weeks of amoxicillin/clavulanate and a short course of oral steroids. The second group received 8 weeks of clarithromycin. Sinonasal Outcome Test-20 (SNOT-20) and Lund and Mackay scores were assessed at baseline and after treatment, and GERD Health-Related Quality of Life (GERD-HRQL) questionnaire was evaluated in all patients. Patients with a GERD-HRQL score >8 received esogastroscopy and H pylori detection. Patients were followed during a 10-year period for clinical course and GERD evolution. The 10-year evolution of patients was described in terms of recurrence, medical, and surgical treatments. Results: Thirty-seven patients completed the study; SNOT-20 and Lund and Mackay scores similarly improved in both groups. Amoxicillin/clavulanate group had significantly more adverse reactions than the clarithromycin group (P = .03). After the therapeutic course, 35% (amoxicillin/clavulanate) and 41% (clarithromycin) of patients needed functional endoscopic sinus surgery (FESS). During the long-term follow-up, 54% (amoxicillin/clavulanate) and 40% (clarithromycin) of patients had late CRSnNP recurrence; FESS was performed in less than 15% of cases of recurrence. Gastroesophageal reflux disease complaint’s severity was associated with late recurrence of CRSnNP. Conclusion: Amoxicillin/clavulanate and clarithromycin would be competitive treatments for CRSnNP. Gastroesophageal reflux disease seems to be a negative factor for treatment response and recurrence.