In order to study how physicians choose to use electronic fetal monitoring and interpret tracings, we administered a questionnaire to which 107 practicing obstetricians and 11 experts in electronic fetal monitoring responded. Sixty-one (57%) of the respondents monitored more than half of their deliveries (high users). In comparison to the less frequent users of electronic fetal monitoring (low users), they showed more positive attitudes toward electronic fetal monitoring and were nearly always more likely to perform cesarean sections on hypothetical patients described in the questionnaire. These differences appeared to be due to the high users' higher estimate of danger to the fetus. We also found that most physicians were generally more likely to perform a cesarean section on a high-risk mother than a low-risk mother with the same tracing. The majority of high and low users and nearly all of the experts, however, felt that antepartum risk factors are not of value in deciding what to do about an abnormal tracing. We conclude that there is wide variation in the way in which obstetricians use, interpret, and act on electronic fetal monitoring tracings. Some of these differences may be due to differing attitudes toward electronic fetal monitoring, differences in interpretation of electronic fetal monitoring tracings, and differences in the way obstetricians incorporate maternal risk factors into their decision-making.