Laboratory utilization by clinician specialty groups serving outpatients was monitored before and after requisition redesign. Requisition changes were designed to address compliance and utilization issues and included implementation of test groupings and cascades or ordering algorithms. Data collected included the number of selected tests and test sets ordered during both time intervals and the number of patient office visits. Selected tests for monitoring included CBC counts, metabolic panels, thyroid function tests, hepatic function tests, urine analysis, and send-out testing. Statistical significance was measured using Poisson rates for test ordering. The composite effect was a significant decrease in the overall number of tests ordered per outpatient visit for most specialties, with a shift in ordering practices from panels to individual tests. Utilization rates by specialty groups were characterized by average number of laboratory tests ordered per patient visit.