Measurements of blood alcohol concentration (BAC) were made on patients who presented to an accident and emergency department with acute alcohol intoxication. A correlation of r = 0.418 was noted to exist between BAC as measured by sampling saliva and blood. Blood alcohol concentrations as measured by salivary reagent strip (ALCO-SCREEN, Chem Elec.) were significantly lower (p less than 0.0001) than those determined by gas chromatography of serum. Although such reagent strips offer a rapid measurement of BAC, it is concluded that they are unreliable for the quantitative measurement of BAC in accident and emergency departments.