Diagnosing sinusitis remains a challenge for primary care physicians. There is a need for a simple, office-based technique to aid in the diagnosis of sinusitis without the cost and radiation risk of conventional radiologic imaging. We designed a low-cost near-infrared (NIR) device to transilluminate the maxillary sinuses. The use of NIR light allows for greater interrogation of deep-tissue structures as compared to visible light. NIR imaging of 21 patients was performed and compared with computed tomography (CT) scans. Individual maxillary sinuses were scored on a scale from 0 to 2 based on their degree of aeration present on CT and similarly based on the NIR signal penetration into the maxilla on NIR images. Our results showed that air-filled and fluid/tissue-filled spaces can be reasonably distinguished by their differing NIR signal penetration patterns, with average NIR imaging scores for fluid-filled maxillary sinuses (0.93+/-0.78, n=29) significantly lower than those for normal maxillary sinuses (1.62+/-0.57, n=13) (p=0.003). NIR imaging of the sinuses is a simple, safe, and cost-effective modality that can potentially aid in the diagnosis of sinusitis. Long-term, significant device refinement and large clinical trials will be needed to determine the diagnostic accuracy of this technique.