Viral persistence depends on the successful avoidance of the host's immunologic surveillance system. This review, which focuses specifically on the herpesviruses, delineates several possible strategies for evading or delaying the immune response. One strategy common to all herpesviruses is the establishment of latency, a state in which the virus may be partially or even completely hidden from the immune system. Other proposed mechanisms of immune evasion include interaction of the virus with components of the humoral immune system, virus-induced modulation of cell-surface recognition structures, and virally mediated interference in antigen processing. Additional strategies include molecular mimicry and the ability of one particular herpesvirus to encode an immunosuppressive cytokine. Although a detailed understanding of the molecular mechanisms of herpesvirus-mediated immune evasion is currently lacking, future studies should identify those critical interactions between host and virus that may prove amenable to therapeutic intervention.