Latency is essential to the pathogenesis of cytomegalovirus (CMV) infection and disease. A survey of mouse organs that might contain latent murine CMV (MCMV) DNA was conducted using nested enzymatic amplification of a 200-bp region of exon 4 of the major immediate early gene 1. MCMV DNA was detected in diverse organs including the heart, kidney, liver, lung, spleen, brain, and salivary glands. The total number of organs in which latent MCMV DNA was detected was significantly greater in mice infected at 4 weeks of age (64/70) than in mice infected at 7 weeks of age (40/69). This phenomenon was associated with greater viral replication in the same organs during acute infection. These results indicate that latent MCMV infection is distributed much more widely than previously suspected and is directly correlated with the extent of viral replication during acute infection.