We evaluated carbohydrate-deficient transferrin (CDT) and gamma-glutamyltranspeptidase (gamma-GT) as markers of alcohol intake and change in alcohol intake in white Australian men aged 20 to 63 years who regularly drank 20 to 60 g of alcohol/day (2 to 6 standard drinks), either as weekend (n = 14) or daily drinkers (n = 41). After 4 weeks of familiarization on usual alcohol intake, men were provided with low alcohol beer (24 x 375 ml cans, 0.9%, v/v, two-weekly), and, for 4 weeks, consumed as much or as little as they wished with no additional alcohol permitted. In an alternate 4-week period, the same amount of full-strength beer (4.9%, v/v) was provided, whereas subjects continued their usual amount and pattern of alcohol consumption. The order of experimental conditions was randomized. Retrospective 7-day diaries documented weekly alcohol intake during 4 weeks of familiarization and 8 weeks of intervention. Mean alcohol intake was 345 g/week of alcohol (SD 97) during familiarization. During the last 4 weeks of intervention (study weeks 8 to 12), mean alcohol intake either increased by 360 g/week (SD 138) with the switch from low to high alcohol or decreased by 328 g/week (SD 120) with the reverse. During familiarization (study weeks 1 to 4), alcohol intake was significantly related independently (R2 = 0.21) to mean corpuscular volume (p = 0.008) and uric acid (p = 0.003), but not to gamma-GT (p = 0.22) nor CDT (p = 0.94). Change in alcohol intake was predicted independently (R2 = 0.60) by change in CDT (p < 0.0001) and gamma-GT (p = 0.0003), but not by change in uric acid or mean corpuscular volume. A 10% change in CDT gave 70% sensitivity and 80% specificity to detect a change of at least 2 standard drinks/day; respective values were 68% and 0 for 10% change in gamma-GT. Results were not related to drinking pattern, smoking, age, or weight. CDT, particularly when used as a continuous variable, may have a place in monitoring alcohol consumption, even in men whose alcohol intake is in the 20 to 60 g/day range.