We mailed a checklist survey to 1600 randomly selected pediatricians, family practice physicians (FPPs) and emergency medicine physicians (EMPs) in the United States regarding their management of children with high fever and no focus of infection at various ages: 3 weeks; 7 weeks; 4 months; and 16 months. Completed questionnaires were returned by 211 of 600 (35.2%) pediatricians, 145 of 500 (29%) FPPs and 141 of 500 (28.2%) EMPs. Most pediatricians, FPPs and EMPs would hospitalize a 3- or 7-week-old infant with fever and most pediatricians and FPPs would treat infants of this age group empirically with antibiotics. Most pediatricians, FPPs and EMPs would not hospitalize a 4-month-old or a 16-month-old with high fever with no focus of infection but 44 and 25% of pediatricians, 38 and 24% of FPPs and 41 and 34% of EMPs, respectively, would treat a 4- and 16-month-old child with high fever and no focus of infection with antibiotics. The preferred antibiotic treatment for hospitalized 3- and 7-week-old infants was ampicillin plus gentamicin or ampicillin plus cefotaxime; for older outpatients preferred treatment was amoxicillin or ceftriaxone. We conclude that hospitalization and empiric antibiotic treatment of very young infants (< 2 months of age) with high fever and no focus of infection are preferred by most of the pediatricians, FPPs and EMPs surveyed. Nearly one-half of these physicians would treat 4-month-olds and a fourth would treat 16-month-olds with high fever and no focus of infection with antibiotics as outpatients.