By using a TaqMan assay we monitored longitudinal changes in Mycoplasma genitalium loads in five men with recurrent M. genitalium-positive nongonococcal urethritis. We observed regrowth of M. genitalium persisting in hosts after treatment and a possible association of the increase in the M. genitalium load with emergence of symptoms and signs of nongonococcal urethritis in four of these patients.