Human papillomavirus (HPV) DNA has been detected in the oral cavity of infants and breast cancer tissue, suggesting its vertical transmission through maternal milk. We determined whether HPV is detected in maternal milk and is vertically transmitted by breast-feeding. Informed consent was obtained, and maternal milk samples (n=80) were analysed for high-risk HPV DNA. In 43 women, this DNA was measured in the uterine cervix. In women with positive samples, this DNA was measured in the oral cavities of their children. The domain including HPV E6 and E7 was amplified by polymerase chain reaction using consensus primers, and HPV serotype determined by electrophoresis after restriction enzyme digestion. High-risk HPV-16 was detected in two of 80 samples (2.5%), and in these two cases, high-risk HPV was not detected in the uterine cervix or oral cavity of the child. It was concluded that the infection of HPV in maternal milk is rare (2/80); vertical transmission through maternal milk was not detected in this study (0/80). HPV infection through maternal milk may occur, but its likelihood is low.