The cells of human peripheral lymph collected from leg lymphatic of healthy volunteers have been studied by light- and electron microscopy. More than 80% of the cells were lymphocytes. The rest of the cells were neutrophils, monocytes, phagocytes, intermediate forms between lymphocytes and monocytes, erythrocytes and large cells. Ultrastructurally these large cells had many features in common with the Langerhans cells of normal epidermis and may represent this cell type or a closely related one.