Brief intervention is a promising treatment for heavy drinking. The present study examined the diagnostic value of carbohydrate-deficient transferrin (CDT), mean corpuscular volume (MCV), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and gamma-glutamyltransferase (GGT) in detecting early-phase heavy drinkers for brief intervention treatment in primary health care. Laboratory data were collected from consecutive 20- to 60-year-old, early-phase heavy drinkers (329 males and 136 females), who were willing to undergo brief intervention treatment in five primary health care outpatient clinics. An elevated value of at least 1 of the 5 markers studied was found in 75% of the male and in 76% of the female heavy drinkers. The sensitivities of CDT, MCV, AST, ALT and GGT values were low; in men, respectively, 39%, 28%, 12%, 28%, and 33%, and in women 29%, 40%, 20%, 29%, and 34%. However, marker combinations, including CDT, reached a good level of sensitivity; the best triple combination (CDT or MCV or GGT) was positive in 69% of the men and 70% of the women. According to logistic regression, the age of the patient had an increasing effect on MCV, ALT and GGT. High body mass index increased all transaminases and decreased CDT and MCV. Smoking increased MCV and decreased AST. Thus, primary health care marker combinations, especially those including CDT, should be considered for the detection of early-phase heavy drinkers for brief intervention treatment.