PURPOSE: This study was conducted to investigate infant temperament and mother-infant attachment of breast-feeding mothers with a 5 ~ 7 month old infant. METHODS: This study was descriptive research. The subjects were 258 infants and their mothers participating in 'Year 2007 Healthy Breastfed BabyContest' on September 5, 2007 and visiting a community health service center from September 1 to December 30 in 2007. The data was gathered by structured questionnaires about the Maternal Attachment Inventory (MAI) and What My baby is Like (WBL). RESULTS: The mean score of WBL was 6.75 and that of MAI was 3.88. In addition, there was a significant positive correlation between the score of infant temperament and mother-infant attachment (r = .33, p < .01). CONCLUSION: Breast-feeding mothers perceived infant's temperament as more positive, therefore, breast-feeding should be encouraged.