BACKGROUND: This study was designed to test the hypothesis that incorrect sucking technique and pacifier use are factors contributing to breastfeeding failure. METHOD: The nursing patterns of 82 exclusively breastfeeding mother-infant pairs were observed 4 to 5 days postpartum on the maternity ward at University Hospital in Malmö, Sweden. The breastfeeding outcome and pacifier use was assessed by regular telephone contacts during a 4-month follow-up. RESULTS: The breastfeeding rate at 4 months was 91 percent in the nonpacifier group and 44 percent in the pacifier group (p = 0.03). An incorrect superficial nipple-sucking technique at the breast from the start combined with pacifier use resulted in early weaning in most cases. CONCLUSION: To promote successful breastfeeding and to reduce nursing problems, an incorrect sucking technique should be prevented or corrected, and the use of pacifiers should be avoided or restricted.