Pain accruing from nipple lesions caused by inadequate latching by the baby is a common complaint among breastfeeding women and an important obstacle to successful breastfeeding. Nipple pain occurs during the first days after delivery and is considered one of the main causes for early weaning. To investigate the efficacy of low-level laser therapy as a treatment for nipple pain due to breastfeeding. A triple-blind, randomized, clinical study. A university-affiliated hospital in São Paulo, Brazil.