To review the curricula and content of 1st- through 5th-year elementary school science textbooks with respect to the presence or absence of terms related to breastfeeding, we conducted a descriptive study analyzing the curricula and 16 textbooks of 25 public schools in 03 municipalities of São Paulo between September 2010 and February 2011. In particular, we defined essential concepts to teach and explain breastfeeding to children. We found that no block themed curriculum explicitly addressed the theme of breastfeeding. Nine of the sixteen predefined concepts were present in eight of the sixteen textbooks adopted. From the analysis, we identified a new category: Support and help the family. Three textbooks used illustrations associated with artificial feeding. In the program and textbooks, there are several opportunities to introduce this topic. We advise integrating this content into all science textbooks in the early years of elementary school.