FIFTEEN years have elapsed since the human cytomegaloviruses (CMV) were first isolated.^{1 2 3} During this period a partial understanding of the host-parasite relations of these unique viruses has materialized. A fascinating picture emerges of agents that may infect by diverse natural or iatrogenic routes, with man at risk from time of conception. Few humans escape infection during life. Overt evidence of infection — at least as now recognized — may be lacking, although the spectrum of disease known to be produced by the CMV continues to expand. Indeed, the variable consequences of infection are so broad as to impinge in some . . .