Objectives: To investigate the utilization of CBC and CBC with differential (CBC w/diff) tests at University of Alabama at Birmingham Hospital, and to determine if a reduction in CBC w/diff tests could be achieved without negatively impacting patient care. Methods: The quantity of testing and distribution of repeated tests before, during, and after an educational intervention were compared. Results: CBC w/diff tests were ordered 10-fold more frequently than CBC tests. The trauma burn intensive care unit ordered the most CBC w/diff tests, with repeat tests done every 4 or 12 hours. The educational intervention reduced the number of CBC w/diff tests ordered and tests repeated every 12 hours. Conclusions: The educational intervention changed the ordering practices of CBC w/diff and CBC tests. This was sustained after the intervention and no negative effects on patient care were noted. Similar interventions may lead to optimization of ordering practices of other laboratory tests.