ABSTRACT Objective To evaluate the influence of grandmothers of infants on exclusive breastfeeding, from their perspective. Methods A descriptive cross-sectional study was carried out with 91 women from a hospital in the inland state of São Paulo. By means of a questionnaire, the following data were collected: sociodemographic data of the grandmother, mother and child; duration of exclusive breastfeeding of daughter or daughter-in-law; information on kinship of participant and grandchild; kind of help provided by grandmother; and knowledge about breastfeeding. […]