Background: Emergency departments (ED) provide routine care and testing for sexually transmitted infections (STIs). At St. Michael�s Hospital ED, an inner-city downtown academic hospital, in Toronto, up to 25% of samples were being rejected in a month. This creates challenges which can lead to falsely reassuring patients, untreated infections, and further spreading infections in the community. To reduce the monthly sample rejection rate for diagnostic STI samples from the ED to less than 1% by April 2020. Aim statement: In collaboration with the microbiology department at our hospital we sought to identify the number and main reasons for rejection of STI samples that were collected in the ED using a Pareto chart. We focused on gonorrhea and chlamydia sample collection from all collected sites (i.e.: vaginal, urine, rectum, throat). We did not focus on serology based testing of STIs including syphilis and HIV. We tracked total STI samples collected per month as a balancing measure to monitor if the new workflow changes would discourage ED physicians from ordering the tests altogether. Measures and design: We used Pareto charts, process mapping and fish bone analysis to better understand the reasons for STI sample rejection from Oct 2019 to Dec 2019. Most of the sample rejection took place because of incorrect collection kit being used, incorrect urine volume collection, inappropriate source for test, and no specimen received. To date we have implemented three interventions to reduce STI sample rejection: (1) we have improved stocking and labelling for NAAT/PCR swabs, and for gonorrhea culture swabs, (2) we simplified the computer order entry set for our ED to help physicians navigate the different STI order entry options, and (3) we held department wide educational rounds to improve physician comfort in ordering the correct swabs. Our average STI rejection rate between Mar and Dec 2019 was 11.0% (107/974 collected), while collected data to between Jan and Oct 2020 was 8.5% (69/810 collected). We have not been successful in reaching our target STI test rejection rates. Evaluation/results: Our next steps to further reduce rejection rates include (4) patient-facing posters for improved urine collection in patient bathrooms, and (5) making test labels more