An Alcohol (Ethanol) Serum Diagnostic Test is a clinical blood test used to accurately measure the precise concentration of ethanol—the active alcohol found in beverages—in a person's bloodstream.

Unlike breathalyzers, which estimate alcohol levels from breath, this laboratory test utilizes blood serum to provide highly accurate, definitive quantitative measurements.

Clinicians rely on this test in emergency medical settings to evaluate suspected alcohol poisoning, investigate altered mental states, and ensure patient safety during trauma care. It is also widely utilized for legal, occupational, and forensic drug monitoring programs to confirm recent alcohol ingestion.