Ten male and 8 female students underwent serial breath alcohol concentration (BrAC) measurements on a CAMIC Datamaster on two consecutive occasions, early evening and again the following morning. Subjects were fasted for 6 h before receiving alcohol as white wine (12.5% by volume) at doses of 38-45 g for males and 26-37 g for females, consumed over 10 min. Specific individual doses were calculated individually from height and weight (according to the Forrest Method) to give target C0 breath alcohol concentrations of 35 µg/100 ml breath in males and 31 µg/100 ml breath in females. BrAC versus time curves were constructed for each subject and the values of peak BrAC (Cmax), BrAC extrapolated at zero time (C0), time taken to reach peak (Tmax) and rate of elimination (ß) were recorded directly from the curves. Values of C0 taken from the BrAC-time curves varied widely, from 21 to 47 µg/100 ml on visit 1 and from 22 to 45 µg/100 ml on visit 2. Widmark Factors calculated from these C0 values averaged 0.74 (range, 0.59-1.06) in males and 0.73 (range, 0.58-1.05) in females. Elimination rate was higher in the morning than evening in both males (7.4 versus 5.7 µg/100 ml/h) and females (6.9 versus 5.8 µg/100 ml/h). Elimination rates in males and females were not significantly different. Total body water, measured by electronic scales, averaged 58.7% (range, 56.6-63%) in males and 48.3% (range, 40.9-57.6%) in females. Widmark Factors calculated by various established mathematical methods were 0.73-0.77 in males and 0.61-0.64 in females.