Aim: To find out the role of intramaxillary sinus pressure changes in the pathogenesis of headache and facial pain in cases of rhinosinusitis, in order to improve our understanding to the nature of rhinogenic or sinogenic headache. Materials and methods: A cross-sectional controlled study was carried out on 195 patients with maxillary sinusitis (study group) and 12 control normal volunteers. The study group then divided based on the presence of sinus pain. Under local anesthesia, all participants were subjected to anterior antral puncture and intramaxillary sinus pressure measurement using the manometer used in central venous pressure measuring. The value of intramaxillary pressure was measured and recorded. Results: The intramaxillary pressure median and range were 0 (−7.1 to 8) in the study group and 0 (−0.5 to 0.4) in the control group. In the study group, we had found 77 out of 195 patients (39.5%) were with negative intramaxillary pressure values and 62 patients (31.8%) were with positive intramaxillary pressure values. In subgroup A (pain), the median and ranges were −3.8 (−7.1 to 8) compared to 0 (−1.9 to 2.7) in subgroup B (no pain) (p = 0.002). There was no one in the subgroup A with 0 cm water intramaxillary pressure, while in subgroup B, 56 patients (54.9%) were with 0 cm water intramaxillary pressure. Conclusion: The changes in the intramaxillary pressure play a significant role in producing facial pain in cases of sinusitis. Pain was significantly related to both positive and negative pressure values. Clinical significance: Sinusitis may cause headache and facial pain, and in this case, intramaxillary pressure change is one of the main mechanisms causing this sinogenic headache or facial pain.