Candida albicans infection of the nipples and breast ducts is a cause of sore nipples and "shooting" breast pain during lactation. A questionnaire which sought to identify predisposing factors was given to 51 women with candidiasis of the lactating breast, 18 women with other breastfeeding difficulties, and 29 women breastfeeding without any difficulties. Nipple damage in early lactation, mastitis, recent use of antibiotics postpartum, long-term use prior to pregnancy, and history of vaginal thrush were positively associated with candidiasis of the lactating breast. Thrush, especially oral thrush, was more common in babies of mothers in the candida group. However, some mothers with symptomatic candida infection reported none of these predisposing factors.