Data from the HealthStyles survey, an annual national mail survey to US adults, were examined to understand changes in public attitudes toward breastfeeding. The 1999 and 2003 HealthStyles surveys included four breastfeeding items related to public attitudes toward breastfeeding in public and toward differences between infant formula and breastmilk. The percentage of respondents in agreement with the statement, "Infant formula is as good as breastmilk," increased significantly from 14.3% in 1999 to 25.7% in 2003. The increase was particularly large among people of low socioeconomic status. The percentage increase in agreement that "feeding a baby formula instead of breastmilk increases the chances the baby will get sick" grew at a statistically significant level, but the total change was small (2.7 percentage points). No significant total changes were found for the other two survey items. The perception that infant formula is as good as breastmilk would be expected to soften a woman's commitment to breastfeeding should she be faced with obstacles to doing so. The findings underscore the need to educate the general public that breastfeeding is the best method of feeding and nurturing infants. Pediatricians and other health professionals should recommend human milk for all infants for whom breastfeeding is not specifically contraindicated.