Porphyromonas gingivalis is a Gram-negative bacterium that is classified as an oral pathogen and, together with the bacteria Treponema denticola and Tannerella forsythia, forms a complex that promotes periodontal diseases such as periodontitis and gingivitis. The main virulence factors of P. gingivalis are cysteine proteinases, gingipains, fimbriae, capsule, lipopolysaccharide layer, and outer membrane vesicles. Some of these virulent factors promote the recruitment of the innate and acquired immune system cells, but still, P. gingivalis can penetrate the bloodstream and potentially participate in the promotion of other diseases such as cancers, cardiovascular diseases, metabolic disorders, and neurological diseases. Molecular mechanisms that can affect the occurrence of these diseases mostly include the activation of the pro-inflammatory response via the NF-κB pathway. Although there are indications of a connection between the bacterium Porphyromonas gingivalis and the previously mentioned diseases, their cause-and-effect relationship has not yet been confirmed. However, the possibilities of using drugs that target the removal of the P. gingivalis bacterium as a potential method of suppression or prevention of the mentioned diseases should be researched.