The first case, to our knowledge, of an integumentary form of botryomycosis is reported in a homosexual man with acquired immunodeficiency syndrome. Anal fistula and ischiorectal and gluteal abscesses developed following severe cryptosporidial diarrhea. Grains composed of gram-positive cocci were identified in the suppurative exudate. The grains had attached to multinucleated macrophages, many of which contained clusters of cocci in their cytoplasm. It is postulated that the cocci were able to survive and probably replicate in the cytoplasm of multinucleated macrophages, and were subsequently extruded as grains. These observations suggest a defect in intracellular killing of cocci by the monocyte-macrophage system. This may relate to failure in induction of control of macrophage activity by T4-inducer subsets.