A retrospective survey of 1,135 telephone calls during 1980 and 1981, reporting scorpion envenomation to the Arizona Poison and Drug Information Center, was reviewed. Of these, 438 calls identified Centruroides exilicauda as the offending scorpion on the basis of description of the arthropod and consistency of physical findings and clinical course. Envenomation by C exilicauda occurred primarily in adults during the summer and early fall months of the year. Although most patients (92%) were treated at home with conservative therapy, 8% of patients either came to or were referred to a medical facility. Children younger than 5 years were frequently brought or were referred to either emergency care or inpatient hospital care. We conclude on the basis of this series that despite the historical reputation of lethality associated with envenomation by C exilicauda, most envenomations by this scorpion are relatively minor. The other important observation was that children younger than 5 years appear to be particularly prone to severe toxicity.