The occurrence and fine structure of Merkel cells with melanosomes in the labial epithelium of the dog and cat were studied by electron microscopy. These melanosomes were polarized in the Merkel cell cytoplasm opposite to the major aggregation of dense-cored granules and the closely abutting nerve terminal. None of melanosomes was found in the Golgi complex region where a few immature dense-cored granules were observed. This may suggest that the melanosomes are not produced in the Merkel cell, but are taken from the melanocytes like in keratinocytes. The possible phagocytotic ability of Merkel cells is discussed.