Introduction:
Parasitic diseases are caused by many species of protozoa, helminths, and arthropods. Parasitosis can be divided into gastrointestinal, tissue and skin diseases and can appear in many different parts of the body. The most common route of transmission is via ingestion. The oral cavity may be a place of colonization for pathogens, resulting in lesion formation.

Objective:
The aim of the study is to characterise and describe the most important symptoms of parasitic diseases that can be diagnosed during dental examination.

Abbreviated description of the state of knowledge:
In this study there are discussed diseases caused by the most common protozoa and the nematodes in the oral cavity. Leishmaniasis is caused by Leishmania spp. protozoa, and its most common symptom observed in the oral cavity are painful ulcerations. Toxoplasmosis usually manifests itself through enlargement of the lymph nodes, and the appearance of antibodies in saliva. Entamoeba gingivalis and Trichomonas tenaxcause periodontitis chronica and inflammation of the soft tissue. The first of the nematodes, Gongylonema pulchrum, is the reason for, among others, the itchy sensation of a moving foreign body under the mucosa. The most common symptoms of Ancylostoma infection are erythematous papules. Filariae causes an infection that manifests through swelling, abscesses, and painless nodules inside the mouth.

Conclusions:
New pathogens are emerging worldwide and pose a threat to health. They can manifest their symptoms in the oral cavity, but the diagnosis of the disease by the dentist is not easy and requires interdisciplinary knowledge and consultation.