The spermatozoa of six varieties of snake (Lampropeltis getulus, Coluber constrictor, Drymarchon corais, Crotalus adamanteus, Micrurus fulvius, and Constrictor spp.), examined in the fresh state by phase-contrast microscopy, appeared identical. Each spermatozoon had an elongated conical head, a short thick neck, and a mitochondrial coat covering two-thirds of the tail. Study of the fine structure of the Lampropeltis spermatozoon showed (a) that the mitochondrial coat consists of four or five separate strands wound spirally about the tail, (b) that a ring of nine coarse fibers surrounds the axial filament, fibers 3 and 8 being the thickest, (c) that both proximal and distal centrioles consist of a ring of nine triplet fibers, each group having a fine, electron-dense column lying along its central aspect, (d) that the neck contains a specialized structure, the “neck cylinder”, within which the coarse tail fibers form a cage about the distal centriole, and (e) that the coarse fibers appear to originate from the proximal centriole and could be regarded as peripheral centriolar products.