Effective pathology services require timely communication of patient-related information between the laboratory and clinicians. The aim of this study was to measure the effect of a computerized provider order entry (CPOE) system on the frequency with which clinicians notify the Hematology Laboratory of details on heparin or warfarin treatments when ordering activated partial thromboplastin time (aPTT) or the prothrombin time (PT) and international normalized ratio (INR). Although information about the total number of patients on warfarin or heparin was unavailable, it was possible to ascertain that the percentage of abnormal results for each year ranged from 39% in 2005 to 45%, 40%, and 38% in the years 2006 to 2008. The proportion of order requests that reported whether patients were on warfarin or heparin increased from 3% of the aPTT tests (253 of 8307) and 1.9% of the PT and INR requests (161 of 8433) in August through September 2005 (before the CPOE was implemented) to 3.9% (393 of 9990; P < .001) and 2.6% (282 of 10814; P  =  .009), respectively, in August through September 2008 (after CPOE implementation). During that period (2005-2008), the median turnaround time for the laboratory decreased from 28 to 21 minutes for the PT and INR test results (P < .001) and from 34 to 23 minutes for the aPTT test results (P < .001). The results show that CPOE and decision-support systems can enhance laboratory efficiency and improve its contribution to effective patient care.