A total of 18 healthy human subjects were used in the study for breath-to-breath comparisons, and 15 subjects provided two blood samples approximately 1 hour apart for blood-breath correlations. Subjects were instructed to eat a normal breakfast prior to drinking and then drink an alcoholic beverage of their choice at a consumption rate between 0.49 and 1.39 g/kg/h of alcohol for approximately 2 hours. Starting about 30 minutes after drinking stopped, subjects provided breath samples over a period ranging from 2 to 5.5 hours. IR analyzers and the Breathalyzer showed a high degree of correlation with blood samples, although all three instruments underestimated blood results. In breath-to-breath comparisons, the Intoxilyzer underestimated the Breathalyzer, while the Alcotest overestimated the Breathalyzer. 21 references, 3 tables, and 6 figures