Ciliogenesis in human oviduct epithelium was studied with transmission and scanning electron microscopes. Both centriolar and acentriolar pathways were involved in duplication of centrioles. The plasma membrane surrounding the base of new cilia invaginated toward the distal end of the basal body during formation of transitional fibers. Fibrous granules were involved in development of striated rootlets in addition to formation of centrioles. The tips of rootlets elongated in fibrils with a banding pattern different from that of usual rootlets; further the fibrils' tips were laterally connected to cell organelles (mostly mitochondria). Ciliogenic cells in early stages contained secretory granule-like vesicles, suggesting that ciliogenic cells are differentiated from secretory cells. The ordinary course of ciliogenesis was disturbed in some ciliogenic cells, resulting in formation of various ciliary abnormalities. Intracytoplasmic ciliated cysts, cilia within periciliary sheaths, and intracytoplasmic axonemes were formed due to disturbance of migration of duplicated centrioles. Swollen cilia and some compound cilia were developed during ciliary elongation.