EN
On the basis of literature data a review is given of some current problems associated with protozoan parasites. These are: occurrence of sexual process in trypanosomes, biology and taxonomy of Cryptosporidium with remarks on the grounds of coccidian system, incidence and life cycle of Pneumocystis carinii, new findings in the biology of Myxosporidia, the problem of Myxosoma cerebralis - Triactinomyxon, the phenomenon of endogeny in the development of myxosporidian plasmodia, alternative ways in the life cycle of Microsporidia. Changes in the "great systematics" of Protozoa - formation of the kingdom Protista and its implications for protoparasitology are also considered.