Although the "Boston exanthem" has been seen rarely over the past 20 years, in the summer of 1974 we identified ten children, aged 1 week to 7 years with echovirus 16 infections. Seven of the children had rashes, and in four, the illness suggested roseola infantum. Five of these children were neonates, all with illnesses severe enough to mimic sepsis. In addition information obtained on echovirus 16 isolations occurring in 1974 elsewhere in the country showed an additional 27 isolations from eight states. It is postulated that more outbreaks of the Boston exanthem or other echovirus 16 illnesses will appear during the next several years, before the virus again "disappears".