The findings fail to support the existence of sporadic fluctuations or spiking in the blood alcohol concentration-time profile during the post-absorptive state. The method of headspace gas chromatography used to determine the concentrations of ethanol in blood and plasma had a standard deviation of 0.28 mg/dl for whole blood and 0.26 mg/dl for plasma; the coefficients of variations were 0.43 percent and 0.79 percent, respectively. The physiological variation from time-to-time, expressed as the residual standard deviation after fitting the ethanol concentration-time regression relationships, ranged from 0.43-3.7 mg/dl (0.65-16 percent). The time-to-time variations in concentrations of ethanol were maximum when there were problems in getting an unimpeded flow of blood through the indwelling catheters. The study emphasizes the need to control carefully the method of sampling blood and in this way keep pre-analytical sources of variation to a minimum. 2 figures, 1 table, and 28 references (Author abstract modified)