The prevalence of subclinical infections caused by cytomegaloviruses (CMV) and herpes simplex viruses (HSV) was assessed simultaneously in the genital and urinary tracts of 1, 101 indigent women. Shedding of CMV from the genital and urinary tracts exceeded that of HSV by ninefold (8.89% vs. 0.95%) and sevenfold (3.8% vs. 0.51%), respectively. Pregnancy, regardless of gestational age, had no discernible influence on productive infection with either virus in either the genital or the urinary tract. In contrast, age was a significant variable, especially with CMV. The prevalence of CMV shedding decreased steadily with age, from peak values of 15% and 8% in the genital and urinary tracts, respectively, of females 11-14 years of age to undetectable levels in females 31 years of age and older. Productive HSV infection was more prevalent in postmenopausal than in premenopausal women: 2.4% vs. 0.8% and 3.1% vs. 0. 2% in the genital and urinary tracts, respectively. Likewise, HSV infection of both the genital and the urinary tract combined was more common in older than in younger females. © 1979 by The University of Chicago.