Light- and electron-microscopical techniques were used to study the structure of the inferior conjunctiva of monkeys including the third eyelid (nictitating membrane). The cell layers of the conjunctival epithelium were 8–10 at the margin, 6–8 near the limbus and 2–4 in other areas except in the third eyelid where there were 1–4 layers. The epithelium was 90–100 µm thick at the margin and 35–40 µm at the other areas except at the third eyelid where it was 10–45 µm thick; near the limbus it was 55–60 µm thick. The morphological differences between the epithelia of the various areas of the inferior conjunctiva are highlighted. The similarities and differences between the human and monkey inferior conjunc