This manual is made up from the laboratory notes of an emergency course given at the University of Illinois. It contains brief descriptions and diagnostic figures of the Protozoa found in the digestive tract, circulatory system and tissues of man. Technics for their preparation for microscopic examinations are also given. Keys for the differential diagnosis of the intestinal amebas and flagellates are provided. The illustrations are excellent but too limited for critical work on the life cycles of some species. It is a convenient handbook for use in the clinical laboratory.