The appearance of peripheral neurons within the skin during embryonic development of the leech is described. These neurons were labeled using a monoclonal antibody, Lan3-6, which recognizes antigens in both the cell body and the axons of these cells. Within the 5 annuli that are found in each midbody segment, peripheral neurons first label in the middle and last in the most anterior and posterior ones. In each annulus, the number of cells labeled is initially 4 and increases as development proceeds. By the end of embryogenesis, all annuli show approximately equal numbers of Lan3-6 labeled neurons. The development of peripheral neurons in the skin of the rear sucker is also described.