BACKGROUND: Breast engorgement is a painful and unpleasant condition affecting large numbers of women in the early postpartum period. During a time when mothers are coping with the demands of a new baby it may be particularly distressing. Breast engorgement may inhibit the development of successful breastfeeding, lead to early breastfeeding cessation, and is associated with more serious illness, including breast infection. OBJECTIVES: To identify the best forms of treatment for women who experience breast engorgement. SEARCH STRATEGY: We identified studies for inclusion through the Cochrane Pregnancy and Childbirth Group's Trials Register (February 2010). SELECTION CRITERIA: Randomised and quasi-randomised controlled trials where treatments for breast engorgement were evaluated. DATA COLLECTION AND ANALYSIS: Two review authors assessed eligibility for inclusion and carried out data extraction. MAIN RESULTS: We included eight studies with 744 women. Trials examined a range of different treatments for breast engorgement: acupuncture (two studies), cabbage leaves (two studies), cold gel packs (one study), pharmacological treatments (two studies) and ultrasound (one study). For several interventions (ultrasound, cabbage leaves, and oxytocin) there was no statistically significant evidence that interventions were associated with a more rapid resolution of symptoms; in these studies women tended to have improvements in pain and other symptoms over time whether or not they received active treatment. There was evidence from one study that, compared with women receiving routine care, women receiving acupuncture had greater improvements in symptoms in the days following treatment, although there was no evidence of a difference between groups by six days, and the study did not have sufficient power to detect meaningful differences for other outcomes (such as breast abscess). A study examining protease complex reported findings favouring intervention groups although it is more than 40 years since the study was carried out, and we are not aware that this preparation is used in current practice. A study looking at cold packs suggested that the application of cold does not cause harm, and may be associated with improvements in symptoms, although differences between control and intervention groups at baseline mean that results are difficult to interpret. AUTHORS' CONCLUSIONS: Allthough some interventions may be promising, there is not sufficient evidence from trials on any intervention to justify widespread implementation. More research is needed on treatments for this painful and distressing condition.