OBJECTIVES: To assess the utility of a new Health Employer Data and Information Set (HEDIS) measure for care quality in treatment of pediatric pharyngitis in an Israeli HMO, develop a comparable measure, and estimate baseline performance. METHODS: Data sources included physician visit, pharmacy purchase and laboratory result files. We selected physician visits in 2003 bearing diagnoses corresponding to ICD-9-CM groups 034, 462 and 463 among children ages two to 18 years. Visits by children for whom antibiotics had been purchased in the preceding 30 days or who had additional diagnoses were excluded. Antibiotic treatment was defined as purchase within three days of the visit of any antibiotic prescribed by the physician who recorded the diagnosis of pharyngitis. The first encounter meeting inclusion criteria for each child was selected. Testing for streptococcal infection was defined as a throat culture or rapid strep test in laboratory files, or record of throat swab or rapid test during a visit, any time from three days prior to the visit until three days after the visit. RESULTS: Fifty-one percent of visits for pharyngitis among children ages 2-18 years were associated with an antibiotic prescription. A total of 76,399 first encounters for pharyngitis were associated with antibiotic treatment in 2003; 34% were accompanied by strep testing. Frequency of testing varied by administrative region, from 30% to 39%. CONCLUSIONS: Utilization of strep testing in association with antibiotic treatment of pediatric pharyngitis (as measured according to HEDIS criteria) was low in Maccabi Healthcare Services in 2003 in comparison to performance in US commercial and Medicaid health plans. In calculating this measure, we assumed complete reporting of rapid strep tests performed in physicians' offices. Refinement of this measure will require verifying this assumption, as underreporting by physicians would result underestimation of performance.