Over 5100 bacterial viruses have been examined in the electron microscope since 1959. About 4950 phages (96%) are tailed and only 186 phages (3.6%), are cubic, filamentous, or pleomorphic. Phages belong to 13 virus families and occur in over 140 bacterial genera. Phages are listed by morphotypes and host genera. Siphoviridae or phages with long, noncontractile tails comprise 61% of tailed phages. The distribution of phages in different bacterial phylogenetic divisions is shown.