Measles is one of widely spread virus infections that is a major cause of deaths in some tropical areas. The measles virus is a member of the genus of Morbillivirus of the family of Paramyxoviridae. The virions contain six polypeptides, including one glycoprotein; two of them are surface proteins that possess hemagglutinating and hemolytic activities, one of them is polymerase. Replication of the measles virus is similar to that of other Paramyxoviruses. Besides the acute infection for measles virus a persistent infection is characteristic that affects central nervous system and inner organs. Molecular mechanisms of it were studied and the results are discussed to explain the pathogenesis of subacute sclerosing panencephalitis, systemic lupus erythematosus and other diseases in which measles or measles-like virus may be involved.