We measured the hepatitis B (HB) vaccination uptake in 249 London babies born in 2004 to HBsAg positive mothers. Two thirds (69%) received three vaccinations and half (49%, 95% CI 43-56) received a complete course (four doses). Complete immunization was associated with sector of delivery (p<0.001), recording of the GP details in case notes, having booked for antenatal care, having a good command of English, and receipt of written information on HB. A third of the babies (33%) had a post-vaccination test; when the mother had other children, 39% of the oldest children were vaccinated; information on partner's vaccination was available for 12%. This study highlights that appropriate counseling and information should be provided to the mothers, and the importance in London of arrangements for integrated care across acute and primary care services.