OBJECTIVES: The aim of the study was to determine whether a system process change improved successful read-back of critical values by the appropriate provider. METHODS: The study implemented a system process change of switching the "first call" physician from the admitting physician to the most recent document writer. Data were compared before (N = 301) and after the intervention (N = 201). Predictor variables included patient factors, physician factors, and environmental factors. The outcome variables measured were successful read-back within 5 and 30 minutes. RESULTS: < 0.001). CONCLUSIONS: We recommend the use of the physician who has most recently engaged with the patient as documented in the medical record for the daily note as the primary source of contact for reporting critical values.