An arterial blood gas (also called "ABG'S") is a blood test that is performed specifically on arterial blood, to determine the concentrations of carbon dioxide, oxygen and bicarbonate, as well as the pH of the blood.

Its main use is in pulmonology, to determine gas exchange levels in the blood related to lung function, but it is also used in nephrology, and used to evaluate metabolic disorders such as acidosis and alkalosis.

As its name implies, the sample is taken from an artery, which is more uncomfortable and difficult than venipuncture.