14 German blood alcohol laboratories took part in an interlaboratory study for blood alcohol (ethanol) determination using a spiked quality control serum sample containing 1.36 g ethanol/L serum (1.10 g ethanol/kg whole blood). They examined the sample during 20 days in order to examine the scheduled value which was confirmed (1.11 g ethanol/kg whole blood). A total of 1120 individual ethanol determination were performed. As expected, the study proved that the average values found for the GC method and for the ADH method are not significantly different. The average bias between the GC and ADH measurements was -0.003 per mille (-0.3 %). According to the results of the study which was conducted in a concentration range above which in Germany driving under alcohol is sanctioned in terms of driving inability, we propose an absolute value of 5 % as a maximum allowable bias between the two alcohol determination procedures. This proposal relates to the control of precision and accuracy of each of the two methods and to in house setpoints of quality control samples which need to be determined during a 20 days period prior to their use as control sample in order to confirm scheduled values given by the provider.