The iatrogenic mechanism of maxillary sinus infection is increasing common in clinical practice now. According to different authors, the proportion of cases of iatrogenic odontogenic maxillary sinusitis (IOMS) in the pattern of odontogenic maxillary sinusitis (OMS) is 55.97-90%. In a number of cases, endodontic treatment, exodontia, dental implantation, and sinus lift surgery are followed by perforation of the Shneiderian membrane and penetration of foreign bodies into the sinus or formation of an oroantral fistula, which may give rise to IOMS. In ostiomeatal complex (OMC) pathology, the risk of maxillary sinusitis on the side of intervention is higher during sinus lift surgery and dental implantation. Foreign bodies, such as tooth fragments and roots embedded in the maxillary sinus during their removal, as well as filling material and dental implants migrated in the sinus, are a common cause of the disease. The materials for tooth pulp treatment contain components that promote the growth of the fungal microflora and the formation of mycetoma. OMC obstruction and edema of the mucosa due to its inflammation are an important determinant of the occurrence and development of chronic sinusitides. Outflow obstruction from the sinus and congestion of its content occur in both rhinogenic and odontogenic maxillary sinusitis. In OMS, delayed mucociliary transport was more obvious than that in rhinogenic maxillary sinusitis. The representatives of gram-negative nonclostridial anaerobic bacteria and -lactamase-producing microorganisms are major pathogens of OMS. The specific features of OMS are its subtle clinical presentation in some cases, which leads to its delayed diagnosis. Paranasal sinus computed tomography is the gold standard for diagnosing OMS. Considering the fact that OMC pathology is an important factor of IOMS, it is necessary to perform an endoscopic examination of the nose and middle nasal passage area. Surgery is used to treat IOMS. Medical therapy may be used only to abolish recurrences. At the present time, the role of OMC is of interest in the pathogenesis of OMS.