ABSTRACTIntraepidermal free nerve endings were studied in spotted (black and white) guinea pigs. Specimens were obtained from black, gray, and white areas. Twenty blocks were made from each area and sections were examined by electron microscopy. Intraepidermal free nerve endings were found in the interfollicular epidermis of all three areas. The distribution density for the black areas was about twice that for the white areas. The frequency in the gray areas was intermediate between that for the black areas and that for the white areas. Intraepidermal free nerve endings contacted the melanocytes directly in the interspaces between the basal lamina of the epidermis and the cytomembrane of the melanocyte or the dendrite of the melanocyte in the intercellular spaces between basal keratinocytes. In most cases, their axons were ensheathed by Schwann cells. In some cases, a part of the axon expanded like a balloon about 200–300 nm in diameter. The ballooning structure contained several vacuoles about 40–60 nm in diameter. These vacuoles seemed to have been secreted into the extracellular spaces. In such cases, an accumulation of dense materials was observed along the opposed membrane of the vacuole and the cytomembrane of the melanocyte. In other cases, the cytomembranes of axons and those of melanocytes seemed to form synapse‐like struc