Lower airway infection is a major cause of morbidity and mortality in patients with cystic fibrosis. It is currently unknown if the infection of the upper airway can cause exacerbation of lower respiratory tract infection. This study aimed to determine the microbiological profile of the anterior paranasal sinuses outflow tract (middle meatus) of cystic fibrosis outpatients. The microbiological profile was defined using endoscopically directed middle meatal cultures. Paired middle meatal and sputum specimens were collected from 56 outpatients for aerobic cultures. A semi-quantitative leukocyte count of the middle meatal samples was performed. The median age of patients was nine years (3-20 years). Staphylococcus aureus (37%), Staphylococcus coagulase-negative (25%), Neisseriac (14%), Pseudomonas aeruginosa (11%), and Streptococcus pneumoniae (7%) were the most prevalent microorganisms in the middle meatal cultures. Using the middle meatal leukocyte count, 16 out of 54 patients (29.6%) presented sinus infection. The most frequently identified pathogens in patients with sinus infections were Staphylococcus aureus (10 patients), Pseudomonas aeruginosa (4 patients), and Streptococcus pneumoniae (3 patients). Agreement of paired middle meatal and sputum cultures was significantly higher among patients with infection in middle meatal (69%). The most common middle meatal pathogens were the typical cystic fibrosis spectrum. This suggests the potential for participating in post-nasal lower airway seeding