The authors review the breath alcohol measurement method based on infrared absorptiometry and its literature. In a comparative study a person's breath alcohol content was measured by either Siemens Alcomat or Seres Ethylometer instrument in routine road-blocks controls and in experiments and was compared to his/her blood alcohol level. Using the conversion factor of 2100:1 there was a high correlation between the breath and blood alcohol levels using either instrument. Despite using a single method either Siemens Alcomat or Seres Ethylometer 679-TH instrument can be recommended for evidential breath alcohol testing of driving under the influence of alcohol in routine road-blocks controls.