Emergency department (ED) overcrowding and prolonged patient length of stay (LOS) is an increasing problem in most American hospitals. Some reports in the literature have suggested that point-of-care (POC) testing may help alleviate ED overcrowding by providing rapid test results to aid in triage decisions and administration of appropriate therapy. In our hospital, a limited menu of POC tests was shown to decrease ED LOS and reduce the number of hours the ED was on divert status. In recent years, the menu of tests available in POC formats has continued to expand raising the possibility that more patients could receive rapid POC results and potentially have a greater impact on ED operations. We analyzed ED laboratory test ordering patterns to determine what impact an expansion of the ED POC menu might achieve using a selected group of instruments. The ED at Massachusetts General Hospital evaluated approximately 76,000 patients in 2005, of which 25% are admitted. Of these, approximately 76% received laboratory testing. The average number of tests per patient for those that received testing was 7.7 assuming scoring of standard medicare panels as one test for the panel, and 75% of patients had 5 or more tests/panels ordered. Of tests performed in our ED, 9% are now performed at the POC in our satellite laboratory (blood glucose, cardiac markers, dipstick urinalysis, urine pregnancy testing, and rapid Strep A and influenza testing) and 66% of patients that receive testing have some test performed at the POC. Overall, the most common laboratory tests requested are the basic metabolic panel (15.0% of tests), complete blood count (13.2%), calcium/phosphate/magnesium (9.7%), hepatic panel (6.7%), urinalysis (6.2%), cardiac markers (5.2%), prothrombin time (5.1%), amylase/lipase (4.8%), urine pregnancy (4.1%), toxicology (2.9%), and partial thromboplastin time (2.8%), respectively. Of patients that received testing, 88% had a complete blood count; 86%, a basic metabolic panel; 68%, a calcium/phosphate/magnesium; 58%, a hepatic panel; 47%, a urinalysis; 39%, a prothrombin time; 36%, an amylase/lipase; 32%, a urine pregnancy; 28%, cardiac markers; and 2.1%, a toxicology analysis. Of all tests, 71.6% were chemistries, 23.4% were hematology tests, and 5% were microbiology tests. Using a hypothetical combination of a rapid chemistry analyzer, a conventional hematology cell counter, and other true POC testing devices, 75.6% of the tests requested by our ED could be performed in our satellite laboratory. With this menu, all requested testing could be performed on 62% of patients that receive testing. The remaining 38% would require some other additional test(s) to complete the laboratory evaluation. Point-of-care testing in an ED satellite laboratory at the Massachusetts General Hospital performs a significant number of selected tests. Expanding the menu to include routine chemistry and hematology would permit 62% of all patients that receive testing to be fully accommodated. Unlike previously reported benefits of POC testing, such as cardiac markers, the potential benefits of doing this in terms of improving patient care or ED operations is not yet clear.