The Health Care Cost Institute (HCCI) in collaboration with West Health conducted an analysis of the high prices that employer-based insurance pays hospital outpatient departments for clinical lab tests. We found that insurers are paying, on average, 3 times more for common lab tests such as blood and urine test when billed by hospital outpatient departments compared to independent laboratories. Despite accounting for a third of total ESI use, spending for clinical lab tests rendered at hospital outpatient department accounted for 60% of spending in our ESI sample.