To analyze the association between apical lesions and sinus changes and to evaluate the agreement between the diagnoses of an endodontist, a radiologist, an oral and maxillofacial surgeon, and an otolaryngologist. 385 axial, coronal, and sagittal MSCT scans were selected using an image archiving andcommunication system (PACS). The examinations had been performed between 2018 and 2022. Apical lesions were observed in 36.10% of sinusitis cases, 73.8% of unilateralsinusitis cases, 48.7% of sinus floor discontinuity cases, and 67.2% of cases in which endodontic treatment had been performed. Agreement between the diagnoses made by the endodontist and those made by the other investigators was high for most study variables (k > 0.60). The exceptions were mucosal thickening, for which agreement between the endodontist and the other investigators was intermediate (k=0.397), and the presence of periapicallesions (k=0.010), previous endodontic treatment (k=0.013), and mucosal thickness (k=0.024), for which agreement between endodontists and radiologists was low. Conclusions: There was an association between sinus changes and apical lesions.