Equine dermal fibroblasts persistently infected with equine infectious anemia virus (EIAV) show no alterations in cell morphology or growth kinetics when compared to uninfected cells. The percentage of cells immunofluorescent positive for viral proteins fluctuated, depending upon the stage of the cell cycle, while production of extracellular virus was uniform throughout the cell cycle, increasing only as the cell number increased. This was shown in log versus stationary phase cultures as well as in cultures synchronized by sterum starvation. The establishment of productive infection did not require host cell DNA synthesis. Normal levels of progeny virus were produced in cultures pretreated with mitomycin C and placed in serum-containing medium. Serum-starved cultures, however, did not support EIAV replication as well as other cultures, presumably because synthesis of provirus was inhibited.