We conducted this survey to determine reasons for missed appointments and the relationship between missed appointments, knowledge of diagnosis, and perception of the impact of this diagnosis on pregnancy outcome. We attempted to interview, by telephone, 506 women within 24 hours of their missing an appointment at a high-risk obstetric clinic. Information from 118 respondents was analyzed. The study population was 71% black and 29% white, the average age was 23, and both income and educational levels were low. Seventy-three percent of the women know their medical diagnosis, yet only 30% perceived the problem as a threat. Women who could identify their diagnosis were more likely to evaluate prenatal care positively (P < .006). Women who perceived their condition as a threat seemed to blame lack of transportation less often as a reason for missing an appointment. Many women who missed appointments did not know why they were being seen, and many did not perceive that the care was useful. Effective patient education could improve compliance.