Introduction: The culture of maxillary sinus secretion is the gold standard to the identification of sinusal pathogens, although the procedure to obtain it is painful and invasive. Aim: To compare the cultures obtained from aspiration of the middle meatus by endoscopic via with that from the maxillary sinus. Methods: The inclusion criteria were: clinical signs and symptoms of chronic rhinosinusitis for at least three months, opacity of ethmoidal and maxillary sinuses at CT scan, and presence of secretion from middle meatus on endoscopic examination. Samples were collected from the middle meatus and the canine fossa by endoscopic via and immediately transferred into Stuart transport way and Thioglycolatte broth. Then, they were taken to the laboratory for routine aerobic, anaerobic and fungal culture and Gram smear. Results: 13 patients were enrolled in this study, 8 men and 5 women, with an average age of 33 years. A total of 15 cultures sets were obtained for analysis. The culture yielded a single organism growth in 11 samples, a polymicrobial growth in 3 and no growth in one set. Anaerobic culture was obtained in 7% and fungal elements were isolated in 20%. Exact correlation between cultures obtained from the middle meatus with those from the maxillary antrum was demonstrated in 80% of the patients. Conclusion: This study demonstrated that middle meatus aspiration cultures correlates well with maxillary antral cultures and can be confidently used to guide antibiotic selection and monitor treatment in chronic rhinosinusitis.