The present crossover, controlled study demonstrates that alcohol at a blood concentration of approximately 0.08% reduces the contrast sensitivity (p less than 0.001). The mean contrast sensitivity was 15.03 dB in the control measurements and 14.39 dB in the measurements with alcohol. Brightness contrast sensitivity was measured with white, green, red and blue light, in this sequence. Therefore, the test design may present time effects as well as 'color effects'. The mean decrease in contrast sensitivity was with white light -1.26 dB, with green light -0.88 dB and with red light -0.57 dB. Contrast sensitivity tested with blue light showed even a slight increase with alcohol (+0.12 dB). The time interval between alcohol consumption and the test was important (p less than 0.001). The mean decrease in contrast sensitivity with alcohol in subjects with a short interval of 40 min was less reduced (-0.3 dB) than in subjects with a long interval of 60 min (-0.98 dB). In summary, at moderate doses of alcohol, contrast sensitivity is only moderately decreased and this decrease depends on the time between alcohol consumption and the test.