These complex anorectal conditions are difficult to diagnose because clinical features overlap. In general, an aggressive approach is reserved for hidradenitis suppurativa and necrotizing infections. Patients with Crohn's disease, hematologic disorders, or AIDS are often treated more conservatively, but the correct timing and degree of aggressiveness of surgical intervention may considerably improve the overall outcome. The increasing incidence of AIDS and the frequency with which infected patients present to surgical clinics make it imperative that all surgeons have a working knowledge of the conditions associated with this syndrome. Expertise is required not only to diagnose and treat these conditions but also to protect oneself and others from being inadvertently infected with the HIV. A high index of suspicion and constant vigilance permit the successful resolution of many of these challenging problems.