In a study involving 68 ambulatory patients with known alcohol problems and 68 social drinkers matched for age and sex, a questionnaire about the patients' history of trauma identified 7 out of 10 subjects with drinking problems. In contrast, abnormal values for gamma-glutamyl transferase, mean corpuscular volume, or high-density lipoproteins had only moderate sensitivity (26% to 40%) for identifying alcohol problems but excellent specificity (88% to 99%) for ruling out cases. Similar rates of sensitivity and specificity were found among 61 family practice patients. Diagnostic accuracy was improved by combining tests results, using computer-based logistic regression analysis. This study suggests that a brief questionnaire on history of trauma is valuable for the earlier detection of problem drinking in ambulatory populations, in contrast to laboratory tests, which appear to have high sensitivity only with more chronic alcoholics.