Infections with cytomegalovirus are widespread among populations. The frequency of anti-CMV bodies occurrence in healthy adults is from 40% in Europe to 100% in the Third World countries. The research carried out in Poland on two thousand healthy women at productive age showed in more than half of them the presence of anti-CMV bodies before pregnancy. It is especially significant in the context of the possibility of primary CMV infection in gravidas and the transmission into the fetus. Confirmation of the primary CMV infection in women at an early stage of pregnancy requires further prenatal diagnosis. CMV is asymptomatic in 99% of cases. It is especially dangerous for neonates, in whom heavy cytomegalovirus disease is connected with immaturity of the immunological system, and for people with immunological system disorders (after transplantations or HIV infections). Clinical forms of CMV infections have been presented here, with some of them being illustrated with descriptions of cases observed at the Clinic; methods of CMV infection treatment in various groups of patients, as well as the state of knowledge about anti-CMV vaccine are also presented.