In order for a provider’s Electronic Medical Record system to meet the certification criteria for Meaningful Use, the EMR must demonstrate the ability to transmit electronically various data to public health, including reportable laboratory results and vaccine administration data. The messaging standards included in the Meaningful Use rule are based on the Health Level 7 message format and the LOINC vocabulary for laboratory tests performed. LOINC is a vocabulary of test names that contains very specific and detailed information about each test. The process of establishing data transmission capacity that meets the requirements of public health involves the mapping of locally-established laboratory test codes to the corresponding code in the LOINC vocabulary. In general, this mapping of local codes to LOINC will need to be carried out and maintained by each trading partner sending data to public health. To support Chicago area hospitals in this mapping work, the Chicago Health Information Technology Regional Extension Center (CHITREC) is partnering with the Metropolitan Chicago Healthcare Council, with support from the Chicago Department of Public Health, to hold a LOINC mapping workshop on May 26th.