The NIAID Specimen Repository (NSR) provides receipt, storage and distribution of biological specimens received from institutions conducting NIAID-sponsored clinical trials and observational cohort studies. Presently the repository houses specimens from HIV-related clinical trials and cohort studies. The specimens have been collected over many years. Selection of Study Groups storing specimens in the NSR is guided by scientific priorities of NIAID. The current NIAID Study Groups storing specimens in the NSR are: the Women’s Interagency HIV Study (WIHS) and the Multicenter AIDS Cohort Study (MACS), now called the MACS/WIHS Combined Cohort Study (MWCCS); and the HIV Vaccine Trials Network (HVTN). The NSR also maintains specimens from other smaller NIAID-sponsored studies that have been completed. There are currently over 8 million specimens in the NSR.