The cytoskeleton exerts a direct effect on the function of sperm by influencing the distribution of subcellular organelles and plasma membrane molecules. We have prepared six monoclonal antibodies to Triton X-100-insoluble components of the bull sperm cytoskeleton. One of the antibodies reacts with a detachable portion of the bull sperm acrosome. The remainder include an antibody that recognizes the principal and end piece of the tail and another that is specific to the middle piece. Two of the antibodies yield dissimilar staining patterns of the neck region and the tail, and the final monoclonal antibody stains the subacrosomal region and a detachable acrosomal domain of bull sperm. The cross reactivities of the antibodies with hamster sperm and PtK2 cells are described, as is the recognition of bull sperm polypeptides on western blots. The results suggest that these antibodies will provide interesting insights concerning the role of the cytoskeleton in sperm development and function.