Toxoplasmosis is one of the most dangerous parasitic diseases. It is known that it affects about 3 billion people worldwide. The ubiquity of toxoplasmosis, lack of a clear symptom complex, a long latent period, and a severe impact on certain groups of individuals allows us treat this parasitosis as one of the most dangerous to the human being. In this regard, it is necessary to introduce modern methods of diagnostics and prophylaxis of toxoplasmosis actively thus contributing towards addressing the challenges facing various fields of the applied medicine. The article is aimed at analyzing publications concerning the toxoplasmosis pathogenesis, diagnosis, and prevention as well as specific features in persons with immunity-deficient states, subjects having been exposed to organ transplantation, and in pregnant women.