Hypodermal gland cells in Raillietiella sp. represent a new cell type in pentastomids. They were discovered in infective larvae (intermediate host) and in juvenile raillietiellids (final host) during molting. The ultrastructural development of hypodermal gland cells is described in this report. We think that hypodermal gland cells are class 1 gland cells, which form temporary cilia during molting. Their possible function as releaser-pheromone gland cells is discussed.