Many factors are associated with low breast-feeding rates among black low-income women. This study examines whether, despite such factors, health professionals' prenatal education of black poor women is assoicated with increased breast-feeding rates. Black women born in the United States who attended a midwives prenatal clinic (N = 159) were randomly assigned to two types of prenatal education or were followed up in a control group. All women were interviewed on entry into the study and after delivery of their infants. Women assigned to group classes attended at least one session discussing myths, problems, and benefits of breast-feeding. Women assigned to individual prenatal counseling spoke with a pediatrician or nurse practitioner, who discussed breast-feeding topics similar to those covered in the classes. Women in the control group received no additional prenatal education. The three study groups had significantly different percentages of women who breast-fed (controls 22%, classes 46%, individual sessions 53%). Higher percentages of women in the study groups carried out their prenatal plans to breast-feed (controls 50%, classes 86%, individual sessions 62%) or breast-fed despite prenatal plans to bottle-feed (controls 10%, classes 26%, individual sessions 48%). After multivariable analysis controlling for age, prenatal pians to breast-feed, prior breast-feeding experience, perceived support for breast-feeding, education, gravidity, and employment plans, women in intervention groups had a higher likelihood of breast-feeding than control subjects. These findings suggest that an increase in relatively simple, not-too-time-consuming educational efforts in institutions and offices serving black low-income women might yield significant narrowing of the gap in breast-feeding rates between white affluent women and black low-income women.