The efficacy of alcohol screening questionnaires, the TWEAK, T-ACE, NET, MAST, and CAGE, in detecting periconceptional risk-drinking, > or = 1 oz absolute alcohol/day, was investigated in 4743 African-American women attending an inner-city prenatal clinic who had reported ever drinking. Sensitivity, specificity, positive predictive value, efficiency, follow-up rates, and receiver operating characteristics of the questionnaires were examined to compare the overall effectiveness of the questionnaires and their performance at cut-points defining positive scores ranging from 1 to 3. Relatively little difference between TWEAK, T-ACE, and MAST was seen in the receiver operating characteristic accuracy indices; NET and CAGE lagged behind. Sensitivity/specificity scores for the two questionnaires most sensitive at cut-point 1 were TWEAK (87/72) and T-ACE (83/75). At cut-point 2, sensitivity was optimized with respect to specificity; TWEAK (79/83) was significantly more sensitive than T-ACE (70/85; p = 0.002). At cut-point 3, the two most sensitive tests were MAST (61/92) and TWEAK (59/94). In general, measures of merit were not greatly affected by the time between conception and the administration of the screens. Screening was most sensitive for women interviewed during the first 15 weeks of pregnancy; risk-drinkers tended to delay entry into prenatal care, increasing positive predictive values associated with screening later in pregnancy. This study confirms the utility, when screening for risk-drinking during pregnancy, of brief questionnaires that assess alcohol intake indirectly by asking women about their tolerance to alcohol's effects, psychological consequences of drinking, and significant others' concern about their drinking. It validates T-ACE and provides preliminary data indicating that TWEAK may outperform T-ACE.