Various procedures have been used to extract or detach the acrosomes from ram and bull spermatozoa. Spermatozoa from pooled ram ejaculates, or individual bull ejaculates, were first washed free of the seminal plasma, suspended in Ringer''s solution, and then incubated at 37[degree] C with solutions of sodium hydroxide, sodium carbonate, or cetyltrimethylammonium bromide (CTAB). An alternate procedure consisted of shaking the Ringer''s suspension of spermatozoa with small glass beads. Staining of spermatozoa by the Giemsa or PAS methods showed that the acrosomes were apparently dissolved by 0.0125 N-NaOH, and that they were detached as such by 1.5 mM CTAB or by shaking with glass beads. Nitrogen and sugar determinations on extracts from spermatozoa confirmed the removal of materials from the cells. Because most of the extractable sugar was released in 0.0125 N-NaOH, it is suggested that a structural element, such as the acrosome, was being detached. Release of hyaluronidase from the treated spermatozoa was also observed. Ram sperm extracts contained four antigens, all of which were similar to antigens in ram seminal plasma, as revealed in double-diffusion agar plates. Antisera also had sperm agglutination titres up to 81.