Delineation of the pathogenic potential and assessment of the efficacy of newer therapeutic modalities for a number of viruses have been among the more notable developments in solid organ transplant infections within the past year. Infection caused by the novel herpesvirus, human herpesvirus-6, was proposed to be a significant cause of fever of unknown origin and a predictor of subsequent cytomegalovirus infection. Interleukin-2-primed isologous T lymphocytes led to the complete regression of Epstein-Barr virus-positive post-transplant lymphoproliferative disorder. Although interferon-alpha alone was shown to be largely ineffective as prophylaxis and treatment for hepatitis C virus hepatitis, the combination of interferon-alpha and ribavirin appeared promising. Documentation, within the past year, however, of lamivudine and famciclovir resistance in hepatitis B virus, ganciclovir resistance in cytomegalovirus, and azole resistance inCandida,is a sobering reminder that antimicrobial prophylaxis must be utilized rationally and selectively. Curr Opin Infect Dis 11:411–417. 1998 Lippincott-Raven Publishers