Vomeronasal tissues from four male gnotobiotic calves were prepared for transmission and scanning electron microscopy. Features described include: non-myelinated nerves in the non-neurosensory lamina propria, capillaries in the base of the neurosensory epithelium, sustentacular cells with microvilli 22-26 micron long, neurosensory cells with numerous apical vesicles, cells with cytoplasmic projections containing dense bundles of filaments, and brush cells. The structurally well developed bovine vomeronasal organ is similar in other respects to that reported for a number of other mammals.