BACKGROUND The constant impairment of the immune system caused by lifelong use of immunosuppressive drugs in patients after heart transplantation has a significant impact on oral cavity health. The aim of this study was to analyze the health of the oral cavity in patients after heart transplantation, with particular regard to occurring pathogens. MATERIAL AND METHODS The study included 25 patients after heart transplantation. The research scheme was divided into 2 parts. The first part consisted of a survey on general health and oral hygiene habits. The second part of the examination consisted of an analysis of the health of the oral cavity: the mucosa, periodontium, and hard dental tissues. Particular attention was paid to PET (test for the presence of pathogens causing periodontitis/periimplantitis) and CAT (diagnostic test for the presence of Candida in the oral cavity), which are real-time PCR tests used to detect pathogens causing periodontitis and microorganisms present in oral candidiasis. RESULTS The conducted research and in-depth analysis of the results showed that the oral health condition in patients after heart transplantation is not satisfactory, regardless of the time that has elapsed since the surgery, sex, age, hygiene habits, or the type of immunosuppression used. The oral cavity of patients after heart transplantation is colonized with Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Treponema denticola, and Candida albicans. CONCLUSIONS The cooperation of the dentist with the attending physician at each stage of the treatment should play an unquestionable role.