Neonatal tetanus is the cause of 23 to 73% of neonatal deaths in developing countries and continues to be an important killer in many parts of India. In this nonrandomized cohort study in a rural area in India, tetanus toxoid immunization status was recorded for 1688 pregnant women. Liveborn children were followed up for 30 days for the occurrence of neonatal tetanus. Nonimmunized and partially immunized women were asked their reasons for not receiving tetanus toxoid vaccine. Complete prenatal immunization with tetanus toxoid during pregnancy (two doses 1 month apart) was associated with an 88% reduction in the risk of neonatal tetanus among the newborn children [95% confidence interval (CI) 59 to 98%]. In multivariable analysis only complete immunization and the use of clean instruments for cutting the umbilical cord were independently associated with a reduction in risk of neonatal tetanus. Registration by the health care provider before 29 weeks of gestation, being 5 km or less from the vaccination facility, having two or more contacts with the health provider and having some school education were independently associated with complete immunization. Immunization of pregnant women with tetanus toxoid was the single most effective intervention against neonatal tetanus independent of other interventions.