This 24-month observation study will be conducted in 13 hospitals of 5 provinces in Thailand: Chiang Rai, Chiang Mai, Ubon Ratchathani, Chonburi, and Songkhla. The research team of TRCARC will collect and analyze secondary and de-identified data from the hospitals' databases. In each site, clients who agree to receive Same-Day ART service will go through standard of care procedures at each hospital, which include: post-test counseling and psychosocial support, baseline lab test, clinical screening, and physical examination. The drug regimen prescribed for clients will mirror the first line ART regimen in Thailand's national guideline, which is tenofovir (TDF), emtricitabine (FTC), and efavirenz (EFV). Retention of the clients will reflect that of the hospital's protocol, and CD4 and viral load will be tested according to the national guideline.