Viruses are obligate parasites which are able to infect cells of all living organisms. Multiple antiviral defense mechanisms have appeared early in evolution of the immune system. Higher vertebrates have the most complex antiviral immunity which is based on both innate and adoptive immune responses. However, majority of living organisms, including plants and invertebrates, rely exclusively on innate immune mechanisms for protection against viral infections. There are some striking similarities in several components of the innate immune recognition between mammals, plants and insects, rendering these signaling cascades as highly conserved in the evolution of the immune system. This review summarizes recent advances in the field of innate immune recognition of viruses, with particular interest on pattern-recognition receptors.