Spermatozoa from the reproductive tubules and epididymis of the African lungfish, Protopterus aethiopicus, were examined by scanning, transmission and scanning-transmission electron microscopy. The biflagellate nature of lungfish spermatozoa was confirmed as a general rule by examining large numbers of specimens in the scanning mode. All have two flagella with attached undulating membranes, a short middle piece and a large sperm head without condensation of the nucleus. The various portions of the sperm have been subjected to analysis of the X-rays emitted upon electron bombardment, and the relative concentrations of several elements have been determined.