Necrotizing fasciitis is an uncommon, rapidly progressive soft-tissue infection that is associated with a high incidence of morbidity and mortality. It is usually caused by bacteria and rarely caused by or complicated by a fungus. We report 3 cases of necrotizing fasciitis of the head and neck in patients with uncontrolled diabetes. Fungi were isolated in all 3 cases. In 1 fatal case, the invasive zygomycete Apophysomyces elegans was isolated. Keys to the management of this condition are (1) early isolation of the causative organism by fungal smear and culture, (2) adequate control of diabetes, (3) maintenance of electrolyte balance, and (4) controlled aggressive surgical debridement at an early stage. We emphasize the importance of fungal smears and cultures in the management of this rapidly spreading infection.