Subject. The subject of this case report is infective endocarditis. Objective. The objective is to describe a clinical case under outpatient-polyclinic conditions at the dentist’s (periodontist’s) office. Methodology. Infective endocarditis is one of the most severe coronary vascular diseases associated with high mortality affected by the area and characteristics of infection, the phase of development, the type of a causative agent, the time to start antibacterial therapy, coexisting diseases, the extent of sequelae, surgical treatment and other circumstances. Following the appropriate treatment, more than 70% patients with infective endocarditis achieve recovery. Conclusions. This case report presents clinical manifestations in the oral cavity of a patient with infective endocarditis. The patient did not exhibit specific symptoms of infective endocarditis serving as the basis for the preliminary dental diagnosis and sending the patient to a cardiologist, rheumatologist for examination and treatment. It should be noted that the patient needs the complex treatment of periodontitis, oral cavity sanation, the case follow-up, supportive periodontal therapy and professional oral hygiene on a quarterly basis. These all can significantly improve the patient’s quality of life and longevity.