Project Summary/Abstract The Endocrine Technologies Support Core (ETSC) at the Oregon National Primate Research Center (ONPRC) was founded nearly 40 years ago to provide hormone assay services for the ONPRC community. Since then, the ETSC has grown into an internationally-known assay core offering over 130 unique assays that analyzes 50,000 samples annually for investigators worldwide. In order to provide our users with state-of-the-art technologies, we transitioned our in-house radioimmunoassays to an LC-MS/MS system in 2015, first offering this service to investigators in October 2015. The service currently supports 13 ONPRC investigators and 10 external investigators, and has become so popular that the system is greatly oversubscribed. There is a months-long waiting list for sample analysis and new method development is often delayed for months at a time. Thus, a second instrument is required to keep up with the continually growing demand for this service. This application requests funds for a Shimadzu Nexera-LCMS-8050 liquid chromatography-tandem triple quadrupole mass spectrometry system. This system will be used by NIH-funded investigators engaged in basic, translational, and pre-clinical nonhuman primate projects as well as human clinical trials to generate data to advance our understanding of reproductive health, aging, addiction, and development. The requested system would expand our current LC-MS/MS service and allow us to provide our state-of-the-art LC-MS/MS analyses in a timely manner for the substantial benefit of ongoing studies by investigators at ONPRC, their collaborators, and other external investigators. This new system would relieve congestion on our current over- subscribed system, decrease our substantial wait times, and allow for more new assay development.