Objectives: To evaluate cryoprecipitate and platelet ordering practices after the implementation of real-time clinical decision support systems (CDSSs) in a computerized physician order entry (CPOE) system. Methods: Uniform platelet and cryoprecipitate transfusion thresholds were implemented at 11 hospitals in a regional health care system with a common CPOE system. Over 6 months, a variety of information was collected on the ordering physicians and the number of alerts generated by the CDSSs when these products were ordered outside of the institutional guidelines. Results: There were 1,889 orders for platelets and 152 orders for cryoprecipitate placed in 6 months. Of these, 1,102 (58.3%) platelet and 74 (48.7%) cryoprecipitate orders triggered an alert. The proportion of orders canceled after an alert was generated ranged from 13.5% to 17.9% for platelets and 0% to 50.0% for cryoprecipitate orders. Conclusions: CDSS alerts reduce, but do not eliminate, platelet and cryoprecipitate transfusions that do not meet institutional guidelines.