In three children who were receiving acute lymphoblastic leukemia induction therapy and were severely neutropenic, necrotizing otitis externa developed. Two patients had a probing maneuver to their ear canal. Pseudomonas aeruginosa was isolated in heavy growth from the external canal of three patients and other tissues of one patient. Staphylococcus aureus was cultured from the ear canal and tissues of one patient and Streptococcus faecalis from the ear canal of another patient. Necrotizing otitis externa resolved in two patients after 2 weeks of intravenous antibiotics, debridement, and resolution of neutropenia. One patient required prolonged intravenous antibiotics and several surgical procedures. The occurrence of necrotizing otitis externa in children with acute lymphoblastic leukemia and severe neutropenia, the association of Gram-positive cocci with necrotizing otitis externa, and the importance of protecting anatomic barriers like the external ear canal in immunocompromised patients are emphasized.