The objective of our study was to test the usefulness of some biological markers of alcoholism to detect heavy drinkers, using a structured interview with a 7-day memory as this is currently considered the most reliable technique for determining alcohol consumption. A transversal, observational study was designed with a sample representative of the working population of the province of Alicante seen by the Ibermutua medical service. Participants were selected randomly and classified according to region and sex. The total sample include 1,033 subjects (644 men and 389 women, mean age 36 +/- 11.7 years). Of these 13.5 were heavy drinkers (> 40 g. of alcohol per day), 23.3 moderates drinkers (20-40 g. alcohol per day). Average consumption of alcohol was from 26 g/day + 29.9 grams. In order to quantify the random error, the confidence interval was set at 95. The methods used to test the biological markers were 2 x 2 tables and the calculation of indicators of sensitivity (S). specificity (E), positive predictive value (Vp+), negative predictive value (Vp-) and effectiveness. The highest S was obtained by associating various markers (65.5%), followed by GGT with 53.9%. The GGT/ALP quotient obtained an E of 95.9% and an AST of 92.2%. The GGT/ALP quotient achieved the best effectiveness (85%) and Vp+ (36.2%) and the association of markers the best Vp-at 92.9%, followed by GGT at 91.3%. In spite of the fact that the markers studied do not meet the conditions required to be considered acceptable as screening (S and E > 80%), their use seems appropriate if their limitations are kept in mind (many false negatives). As the GGT/ALP quotient has the highest E, there are few false positives. In order to decrease the number of false negatives, an evaluation of GGT or marker association can be done for those with negative values. In order to resolve the disadvantages of Vp+, the best solution is to order tests for groups of markers that are most prevalent in heavy drinkers.