introduction: breastfeeding is the safest and cheapest strategy for adequate nutrition and protection against infections in infants; it is enough as the only nourishment source during the first six months of life and the best complementary source until the second year after birth. its practice is still insufficient and inadequate. the objective of this study is to discover socio-demographic and health system characteristics, knowledge and practices related to breastfeeding and provision of whole milk. methods: a prospective cross-section study was carried out in the municipality of calarca, department of quindio, with 384 children aged 2 to 5. every mother was interviewed in a protocol for that purpose with previous consent. processing and analysis of data were done with the program spss version 14. results: prevalence of exclusive breastfeeding for children 6 months old was calculated at 24%; this low percentage was associated to the mothers' lack of knowledge (rp: 1.3 ic95% 1.1 - 1.6) and premature start of complementary feeding (mann whitney test p < 0.00). premature nourishment with whole milk was associated with independent factors in a logistic regression such as start of complementary feeding before the fourth month of life (rp 3.9 ic95% 1.7- 9.2) and having two or more brothers (rp 3.3 ic95% 1.3- 8.5). conclusions: lack of knowledge about benefits of exclusive breastfeeding and introduction to whole milk are top priority elements to develop prevention strategies for childhood prevailing diseases.