To study the occurrence of exogenous reinfection with cytomegalovirus (CMV), we examined serial isolates from the cervix, urine, and throat of eight women attending a clinic for sexually transmitted diseases (STD) and seven women receiving routine prenatal care. Isolates were compared by restriction enzyme “fingerprinting” of viral DNA. Four of the eight women from the STD clinic were infected with more than one strain of CMV. Two women shed different strains in serial isolates, and two women shed different strains simultaneously from different body sites. These results suggest that exogenous reinfection is not uncommon in women with a high probability of exposure to CMV.